Humanized non-human animals with restricted immunoglobulin heavy chain loci

ABSTRACT

Mice, embryos, cells, and tissues having a restricted immunoglobulin heavy chain locus and an ectopic sequence encoding one or more ADAM6 proteins are provided. In various embodiments, mice are described that have humanized endogenous immunoglobulin heavy chain loci and are capable of expressing an ADAM6 protein or ortholog or homolog or functional fragment thereof that is functional in a male mouse. Mice, embryos, cells, and tissues having an immunoglobulin heavy chain locus characterized by a single human VH gene segment, a plurality of human DH gene segments and a plurality of human JH gene segments and capable expressing an ADAM6 protein or ortholog or homolog or functional fragment thereof are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC § 119(e) of U.S.Provisional Patent Application No. 61/658,466, filed 12 Jun. 2012, andU.S. Provisional Patent Application No. 61/663,131, filed 22 Jun. 2012;both applications are hereby incorporated by reference in theirentirety.

FIELD

Genetically engineered non-human animals that comprise a reducedimmunoglobulin heavy chain variable gene complexity are provided,wherein the non-human animals are capable of expressing an ADAM6 proteinor functional fragment thereof. Genetically engineered non-human animalsthat express antibodies from a restricted number of immunoglobulin heavychain variable gene segments and/or variants thereof, wherein thenon-human animals lack a functional endogenous ADAM6 gene but retainADAM6 function, are described, including mice that comprise amodification of an endogenous immunoglobulin heavy chain variable(V_(H)) region locus that renders the mouse incapable of making afunctional ADAM6 protein and results in a loss in fertility. Thegenetically modified mice comprise an immunoglobulin V_(H) locuscharacterized by a restricted number of V_(H) gene segments, e.g., asingle immunoglobulin V_(H) segment, e.g., a human V_(H)1-69 genesegment or a human V_(H)1-2 gene segment, and that further compriseADAM6 function are described, including mice that comprise an ectopicnucleic acid sequence that restores fertility to a male mouse.

Genetically modified mice, cells, embryos, and tissues that comprise anucleic acid sequence encoding a functional ADAM6 locus are described,wherein the mice, cells, embryos, and tissues express an immunoglobulinheavy chain derived from a single human V_(H) gene segment. Further, themice, cells, embryos, and tissues lack a functional endogenous ADAM6gene but retain ADAM6 function characterized by the presence of anectopic nucleic acid sequence that encodes an ADAM6 protein. Methods formaking antibody sequences in fertile non-human animals that are usefulfor binding pathogens, including human pathogens are provided.

BACKGROUND

Non-human animals, e.g., mice, have been genetically engineered to beuseful tools in methods for making antibody sequences for use inantibody-based human therapeutics. Mice with humanized variable regionloci (e.g., V_(H), D_(H), and J_(H) genes, and V_(L) and J_(L) genes)are used to generate cognate heavy and light chain variable domains foruse in antibody therapeutics. Mice that generate fully human antibodieswith cognate heavy and light chains are known in the art. For thecreation of these mice, it was necessary to disable the endogenous mouseimmunoglobulin genes so that the randomly integrated fully humantransgenes would function as the expressed repertoire of immunoglobulinsin the mouse. Such mice can make human antibodies suitable for use ashuman therapeutics, but these mice display substantial problems withtheir immune systems. These problems lead to several experimentalhurdles, for example, the mice are impractical for generatingsufficiently diverse antibody repertoires, require the use of extensivere-engineering fixes, provide a suboptimal clonal selection processlikely due to incompatibility between human and mouse elements, and anunreliable source of large and diverse populations of human variablesequences needed to be truly useful for making human therapeutics.

Human antibody therapeutics are engineered based on desiredcharacteristics with respect to selected antigens. Humanized mice areimmunized with the selected antigens, and the immunized mice are used togenerate antibody populations from which to identify high-affinitycognate heavy and light variable domains with desired bindingcharacteristics. Some humanized mice, such as those having ahumanization of just variable regions at endogenous mouse loci, generatepopulations of B cells that are similar in character and number towild-type mouse B cell populations. As a result, an extremely large anddiverse population of B cells is available in these mice from which toscreen antibodies, reflecting a large number of different immunoglobulinrearrangements, to identify heavy and light variable domains with themost desirable characteristics.

However, not all antigens provoke an immune response that exhibits avery large number of rearrangements from a wide selection of variable(V) segments. That is, the human humoral immune response to certainantigens is apparently restricted. The restriction is reflected inclonal selection of B cells that express only certain V segments thatbind that particular antigen with sufficiently high affinity andspecificity. Some such antigens are clinically significant, i.e., anumber are well-known human pathogens. A presumption arises that the Vsegment expressed in the human immune response is a V segment that, incombination with a human D and a human J segment, is more likely togenerate a useful high affinity antibody than a randomly selected Vsegment that has not been observed in a human antibody response to thatantigen.

It is hypothesized that natural selection, over millennia of experiencebetween humans and the pathogen, has selected the most efficientfoundation or base from which to design its most effective weapon forneutralizing the pathogen—the selected V gene segment. There is a needin the art for superior antibodies that bind and/or neutralize antigenslike the pathogens discussed above. There is a need to more rapidlygenerate useful sequences from selected V gene segments, includingpolymorphic and/or somatically mutated selected V gene segments and tomore rapidly generate useful populations of B cells havingrearrangements of the V gene segments with various D and J genesegments, including somatically mutated versions thereof, and inparticular rearrangements with unique and useful CDR3 regions. There isa need for improved biological systems, e.g., non-human animals (suchas, e.g., mice, rats, rabbits, etc.) that can generate therapeuticallyuseful antibody variable region sequences from selected V gene segmentsin increased number and diversity that, e.g., can be achieved inexisting modified animals, while at the same time reducing oreliminating deleterious changes that might result from the geneticmodifications. There is a need for improved biological systemsengineered to have a committed humoral immune system for clonallyselecting antibody variable sequences derived from restricted, selectedV gene segments, including but not limited to cognate human heavy andlight chain variable domains, useful in the manufacture of humanantibody-based therapeutics against selected antigens, including certainhuman pathogens. There remains a need in the art for making improvedgenetically modified mice that are useful in generating immunoglobulinsequences, including human antibody sequences, directed to theelimination of pathogens that burden the human population.

There is a need in the art for therapeutic antibodies that are capableof neutralizing viral antigens, e.g., HIV and HCV, includingantigen-specific antibodies containing heavy chains derived from asingle human variable gene segment. There is also a need for furthermethods and non-human animals for making useful antibodies, includingantibodies that comprise a repertoire of heavy chains derived from asingle human V_(H) segment and having a diverse set of CDR sequencesincluding heavy chains that express with cognate human light chains, andincluding restoration of unfavorable effects resulting from insertion ofhuman genomic sequences into the genome of the non-human animals.Methods are needed for selecting CDRs for immunoglobulin-based bindingproteins that provide an enhanced diversity of binding proteins fromwhich to choose, and enhanced diversity of immunoglobulin variabledomains, including compositions and methods for generating somaticallymutated and clonally selected immunoglobulin variable domains for use,e.g., in making human therapeutics.

SUMMARY

Genetically modified immunoglobulin loci are provided that comprise arestricted number of different heavy chain variable region gene segments(i.e., V genes, V_(H) genes, V_(H) gene segments, or V gene segments),e.g., no more than one, two, or three different V genes; or no more thanone V gene segment family member present, e.g., in a single copy or inmultiple copies and/or comprising one or more polymorphisms, and invarious embodiments the loci lack a sequence that encodes an endogenousfunctional ADAM6 protein.

Loci are provided that are capable of rearranging and forming a geneencoding a heavy chain variable domain that is derived from a heavychain V gene repertoire that is restricted, e.g., that is a single V_(H)gene segment or selected from a plurality of polymorphic variants of thesingle V_(H) gene segment, wherein in various embodiments the loci lackan endogenous functional ADAM6 gene or functional fragment thereof.

Modified immunoglobulin loci include loci that lack an endogenousfunctional ADAM6 gene and comprise human immunoglobulin sequences areprovided, e.g., a human V segment operably linked to a human or (orhuman/non-human chimeric) non-human immunoglobulin constant sequence(and in operable linkage with, e.g., a D and/or a J segment). Modifiedloci that comprise multiple copies of a single V_(H) gene segment,including wherein one or more of the copies comprises a polymorphicvariant, and an ectopic nucleotide sequence that encodes an ADAM6protein or fragment thereof that is functional in the non-human animal,are provided. Modified loci that comprise multiple copies of a singleV_(H) segment, operably linked with one or more D segments and one ormore J segments, operably linked to a non-human immunoglobulin constantsequence, e.g., a mouse or rat or human sequence, are provided.Non-human animals comprising such humanized loci are also provided,wherein the non-human animals have wild-type fertility.

Non-human animals are provided that comprise an immunoglobulin heavychain variable locus (e.g., one a transgene or as an insertion orreplacement at an endogenous non-human animal heavy chain variablelocus) that comprises a single V_(H) segment operably linked to a Dand/or J gene segment. In various embodiments, the single V_(H) genesegment is operably linked to one or more D and/or one or more J genesegments at the endogenous immunoglobulin heavy chain variable genelocus of the non-human animal. In various embodiments, the non-humananimals further comprise an ectopic nucleotide sequence that encodes anADAM6 protein or homolog or ortholog thereof that is functional in themale non-human animal that comprises the modified heavy chain locus. Invarious embodiments, the ectopic nucleotide sequence is contiguous withthe single V_(H) segment, a D gene segment, or a J gene segment. Invarious embodiments, the ectopic nucleotide sequence is contiguous witha non-immunoglobulin sequence in the genome of the non-human animal. Inone embodiment, the ectopic nucleotide sequence is on the samechromosome as the modified heavy chain locus. In one embodiment, theectopic nucleotide sequence is on a different chromosome as the modifiedheavy chain locus.

Non-human animals are provided that are modified at their immunoglobulinheavy chain variable region loci to delete all or substantially all(e.g., all functional segments, or nearly all functional segments)endogenous immunoglobulin V_(H) segments and that comprise a humanV_(H)1-69 segment (or a human V_(H)1-2 segment) operably linked to a Dand J segment or a J segment at the endogenous immunoglobulin heavychain variable region locus of the non-human animal. Non-human animalscomprising such loci and that lack an endogenous ADAM6 gene(s) are alsoprovided.

Methods are provided for making human immunoglobulin sequences innon-human animals. In various embodiments the human immunoglobulinsequences are derived from a repertoire of immunoglobulin V sequencesthat consist essentially of a single human V segment, e.g., V_(H)1-69 orV_(H)1-2, and one or more D and J segments or one or more J segments.Methods for making human immunoglobulin sequences in non-human animals,tissues, and cells are provided, wherein the human immunoglobulinsequences bind a pathogen.

In one aspect, nucleic acid constructs, cells, embryos, mice, andmethods are provided for making mice that comprise a modification thatresults in a nonfunctional endogenous mouse ADAM6 protein or ADAM6 gene(e.g., a knockout of or a deletion in an endogenous ADAM6 gene), whereinthe mice comprise a nucleic acid sequence that encodes an ADAM6 proteinor ortholog or homolog or fragment thereof that is functional in a malemouse. In one embodiment, the mice comprise an ectopic nucleotidesequence encoding a rodent ADAM6 protein or ortholog or homolog orfunctional fragment thereof, in a specific embodiment, the rodent ADAM6protein is a mouse ADAM6 protein.

In one aspect, nucleic acid constructs, cells, embryos, mice, andmethods are provided for making mice that comprise a modification of anendogenous mouse immunoglobulin locus, wherein the mice comprise anADAM6 protein or ortholog or homolog or fragment thereof that isfunctional in a male mouse. In one embodiment, the endogenous mouseimmunoglobulin locus is an immunoglobulin heavy chain locus, and themodification reduces or eliminates ADAM6 activity of a cell or tissue ofa male mouse. In one embodiment, the endogenous mouse immunoglobulinlocus is an immunoglobulin heavy chain locus, and the modificationmaintains or sustains ADAM6 activity of a cell or tissue of a malemouse.

In one aspect, a modified immunoglobulin heavy chain locus is providedthat comprises a heavy chain V segment repertoire that is restrictedwith respect to the identity of the V segment, and that comprises one ormore D segments and one or more J segments, or one or more J segments.In one embodiment, the heavy chain V segment is a human segment. In oneembodiment, the modified immunoglobulin heavy chain locus lacks anendogenous ADAM6 gene. In one embodiment, the modified heavy chain locusfurther comprises a nucleotide sequence that encodes an ADAM6 protein.In a specific embodiment, the nucleotide sequence is contiguous with theV, D and/or J gene segment at the modified immunoglobulin heavy chainlocus.

In one embodiment, the modified locus is a non-human locus. In oneembodiment, the non-human locus is modified with at least one humanimmunoglobulin sequence. In one embodiment, the non-human locus ismodified with at least one human immunoglobulin sequence and a sequencethat encodes an ADAM6 protein.

In one embodiment, the restriction is to one V segment family member. Inone embodiment, the one V segment family member is present in two ormore copies. In one embodiment, the one V segment family member ispresent as two or more variants (e.g., two or more polymorphic forms ofthe V segment family member). In one embodiment, the one V segment is ahuman V segment family member. In one embodiment, the one V segmentfamily member is present in a number of variants as is observed in thehuman population with respect to that variant. In one embodiment, the Vsegment family member is selected from Table 1. In one embodiment, the Vsegment family member is present in a number of variants as shown, foreach V segment, in a number of alleles from 1 allele to the number ofalleles shown in the right column of Table 1.

In one aspect, mice are provided that comprise an ectopic nucleotidesequence encoding a mouse ADAM6 or ortholog or homolog or functionalfragment thereof; mice are also provided that comprise an endogenousnucleotide sequence encoding a mouse ADAM6 or ortholog or homolog orfragment thereof, and at least one genetic modification of a heavy chainimmunoglobulin locus. In one embodiment, the endogenous nucleotidesequence encoding a mouse ADAM6 or ortholog or homolog or fragmentthereof is located at an ectopic position as compared to an endogenousADAM6 gene of a wild type mouse.

In one aspect, methods are provided for making mice that comprise amodification of an endogenous mouse immunoglobulin locus, wherein themice comprise an ADAM6 protein or ortholog or homolog or fragmentthereof that is functional in a male mouse.

In one aspect, methods are provided for making mice that comprise agenetic modification of an immunoglobulin heavy chain locus, whereinapplication of the methods result in male mice that comprise a modifiedimmunoglobulin heavy chain locus (or a deletion thereof), and the malemice are capable of generating offspring by mating. In one embodiment,the male mice are capable of producing sperm that can transit from amouse uterus through a mouse oviduct to fertilize a mouse egg.

In one aspect, methods are provided for making mice that comprise agenetic modification of an immunoglobulin heavy chain locus, whereinapplication of the methods result in male mice that comprise a modifiedimmunoglobulin heavy chain locus (or a deletion thereof), and the malemice exhibit a reduction in fertility, and the mice comprise a geneticmodification that restores in whole or in part the reduction infertility. In various embodiments, the reduction in fertility ischaracterized by an inability of the sperm of the male mice to migratefrom a mouse uterus through a mouse oviduct to fertilize a mouse egg. Invarious embodiments, the reduction in fertility is characterized bysperm that exhibit an in vivo migration defect. In various embodiments,the genetic modification that restores in whole or in part the reductionin fertility is a nucleic acid sequence encoding a mouse ADAM6 gene orortholog or homolog or fragment thereof that is functional in a malemouse.

In one embodiment, the genetic modification comprises replacingendogenous immunoglobulin heavy chain variable loci with a restrictednumber, e.g., no more than one, two or three different heavy chainvariable (V_(H)) gene segments, one or more heavy chain diversity(D_(H)) gene segments and one or more heavy chain joining (J_(H)) genesegments of another species (e.g., a non-mouse species). In oneembodiment, the genetic modification comprises insertion of a singleorthologous immunoglobulin V_(H) gene segment, at least one D_(H) genesegment, and at least one J_(H) gene segment into endogenousimmunoglobulin heavy chain variable loci. In a specific embodiment, thespecies is human. In one embodiment, the genetic modification comprisesdeletion of an endogenous immunoglobulin heavy chain variable locus inwhole or in part, wherein the deletion results in a loss of endogenousADAM6 function. In a specific embodiment, the loss of endogenous ADAM6function is associated with a reduction in fertility in male mice. Inone embodiment, the genetic modification comprises inactivation of anendogenous immunoglobulin heavy chain variable locus in whole or inpart, wherein the deletion does not result in a loss of endogenous ADAM6function. Inactivation may include replacement or deletion of one ormore endogenous gene segments resulting in an endogenous immunoglobulinheavy chain locus that is substantially incapable of rearrangement toencode a heavy chain of an antibody that comprises endogenous genesegments. Inactivation may include other modifications that render theendogenous immunoglobulin heavy chain locus incapable of rearranging toencode the heavy chain of an antibody, wherein the modification does notinclude replacement or deletion of endogenous gene segments. Exemplarymodifications include chromosomal inversions and/or translocationsmediated by molecular techniques, e.g., using precise placement ofsite-specific recombination sites (e.g., Cre-lox technology).

In one embodiment, the genetic modification comprises inserting into thegenome of the mouse a DNA fragment containing a restricted number, e.g.,no more than one, two or three different heavy chain variable (V_(H))gene segments, one or more heavy chain diversity (D_(H)) gene segmentsand one or more heavy chain joining (J_(H)) gene segments of anotherspecies (e.g., a non-mouse species) operably linked to one or moreconstant region sequences (e.g., an IgM and/or an IgG gene). In oneembodiment, the DNA fragment is capable of undergoing rearrangement toform a sequence that encodes a heavy chain of an antibody. In oneembodiment, the genetic modification comprises insertion of a singleorthologous immunoglobulin V_(H) gene segment, at least one D_(H) genesegment, and at least one J_(H) gene segment into the genome of themouse. In a specific embodiment, the species is human. In oneembodiment, the genetic modification comprises deletion of an endogenousimmunoglobulin heavy chain variable locus in whole or in part to renderthe endogenous immunoglobulin heavy chain locus nonfunctional, whereinthe deletion further results in a loss of endogenous ADAM6 function. Ina specific embodiment, the loss of endogenous ADAM6 function isassociated with a reduction in fertility in male mice.

In one aspect, mice are provided that comprise a modification thatreduces or eliminates mouse ADAM6 expression from an endogenous ADAM6allele such that a male mouse having the modification exhibits a reducedfertility (e.g., a highly reduced ability to generate offspring bymating), or is essentially infertile, due to the reduction orelimination of endogenous ADAM6 function, wherein the mice furthercomprise an ectopic ADAM6 sequence or homolog or ortholog or functionalfragment thereof. In one aspect, the modification that reduces oreliminates mouse ADAM6 expression is a modification (e.g., an insertion,a deletion, a replacement, etc.) in a mouse immunoglobulin locus. In oneembodiment, the immunoglobulin locus is an immunoglobulin heavy chainlocus.

In one embodiment, the reduction or loss of ADAM6 function comprises aninability or substantial inability of the mouse to produce sperm thatcan travel from a mouse uterus through a mouse oviduct to fertilize amouse egg. In a specific embodiment, at least about 95%, 96%, 97%, 98%,or 99% of the sperm cells produced in an ejaculate volume of the mouseare incapable of traversing through an oviduct in vivo followingcopulation and fertilizing a mouse ovum.

In one embodiment, the reduction or loss of ADAM6 function comprises aninability to form or substantial inability to form a complex of ADAM2and/or ADAM3 and/or ADAM6 on a surface of a sperm cell of the mouse. Inone embodiment, the loss of ADAM6 function comprises a substantialinability to fertilize a mouse egg by copulation with a female mouse.

In one aspect, a mouse is provided that lacks a functional endogenousADAM6 gene, and comprises a protein (or an ectopic nucleotide sequencethat encodes a protein) that confers ADAM6 functionality on the mouse.In one embodiment, the mouse is a male mouse and the functionalitycomprises enhanced fertility as compared with a mouse that lacks afunctional endogenous ADAM6 gene.

In one embodiment, the protein is encoded by a genomic sequence locatedwithin an immunoglobulin locus in the germline of the mouse. In aspecific embodiment, the immunoglobulin locus is a heavy chain locus. Inanother specific embodiment, the heavy chain locus comprises a singlehuman V_(H), at least one human D_(H) and at least one human J_(H) genesegment. In another specific embodiment, the heavy chain locus comprisesone human V_(H) gene segment, 27 human D_(H) gene segments, and sixhuman J_(H) gene segments. In one embodiment, the ectopic protein isencoded by a genomic sequence located within a non-immunoglobulin locusin the germline of the mouse. In one embodiment, the non-immunoglobulinlocus is a transcriptionally active locus. In a specific embodiment, thetranscriptionally active locus is the ROSA26 locus. In a specificembodiment, the transcriptionally active locus is associated withtissue-specific expression. In one embodiment, the tissue-specificexpression is present in reproductive tissues. In one embodiment, theprotein is encoded by a genomic sequence randomly inserted into thegermline of the mouse.

In one embodiment, the mouse comprises a human or chimeric human/mouseor chimeric human/rat light chain (e.g., human variable, mouse or ratconstant) and a chimeric human variable/mouse or rat constant heavychain. In a specific embodiment, the mouse comprises a transgene thatcomprises a chimeric human variable/rat or mouse constant light chaingene operably linked to a transcriptionally active promoter, e.g., aROSA26 promoter. In a further specific embodiment, the chimerichuman/mouse or rat light chain transgene comprises a rearranged humanlight chain variable region sequence in the germline of the mouse.

In one embodiment, the ectopic nucleotide sequence is located within animmunoglobulin locus in the germline of the mouse. In a specificembodiment, the immunoglobulin locus is a heavy chain locus. In oneembodiment, the heavy chain locus comprises a single human V_(H), atleast one human D_(H) and at least one human J_(H) gene segment. In aspecific embodiment, the heavy chain locus comprises a single humanV_(H), 27 human D_(H) gene segments and six human J_(H) gene segments.In one embodiment, the ectopic nucleotide sequence is located within anon-immunoglobulin locus in the germline of the mouse. In oneembodiment, the non-immunoglobulin locus is a transcriptionally activelocus. In a specific embodiment, the transcriptionally active locus isthe ROSA26 locus. In one embodiment, the ectopic nucleotide sequence ispositioned randomly inserted into the germline of the mouse.

In one aspect, a mouse is provided that lacks a functional endogenousADAM6 gene, wherein the mouse comprises an ectopic nucleotide sequencethat complements the loss of mouse ADAM6 function. In one embodiment,the ectopic nucleotide sequence confers upon the mouse an ability toproduce offspring that is comparable to a corresponding wild-type mousethat contains a functional endogenous ADAM6 gene. In one embodiment, thesequence confers upon the mouse an ability to form a complex of ADAM2and/or ADAM3 and/or ADAM6 on the surface of sperm cell of the mouse. Inone embodiment, the sequence confers upon the mouse an ability to travelfrom a mouse uterus through a mouse oviduct to a mouse ovum to fertilizethe ovum.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence produces at leastabout 50%, 60%, 70%, 80%, or 90% of the number of litters a wild-typemouse of the same age and strain produces in a six-month time period.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence produces at leastabout 1.5-fold, about 2-fold, about 2.5-fold, about 3-fold, about4-fold, about 6-fold, about 7-fold, about 8-fold, or about 10-fold ormore progeny when bred over a six-month time period than a mouse of thesame age and the same or similar strain that lacks the functionalendogenous ADAM6 gene and that lacks the ectopic nucleotide sequencethat is bred over substantially the same time period and undersubstantially the same conditions.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence produces an averageof at least about 2-fold, 3-fold, or 4-fold higher number of pups perlitter in a 4- or 6-month breeding period than a mouse that lacks thefunctional endogenous ADAM6 gene and that lacks the ectopic nucleotidesequence, and that is bred for the same period of time.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence is a male mouse, andthe male mouse produces sperm that when recovered from oviducts at about5-6 hours post-copulation reflects an oviduct migration that is at least10-fold, at least 20-fold, at least 30-fold, at least 40-fold, at least50-fold, at least 60-fold, at least 70-fold, at least 80-fold, at least90-fold, 100-fold, 110-fold, or 120-fold or higher than a mouse thatlacks the functional endogenous ADAM6 gene and that lacks the ectopicnucleotide sequence.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence when copulated witha female mouse generates sperm that is capable of traversing the uterusand entering and traversing the oviduct within about 6 hours at anefficiency that is about equal to sperm from a wild-type mouse.

In one embodiment, the mouse lacking the functional endogenous ADAM6gene and comprising the ectopic nucleotide sequence produces about1.5-fold, about 2-fold, about 3-fold, or about 4-fold or more litters ina comparable period of time than a mouse that lacks the functional ADAM6gene and that lacks the ectopic nucleotide sequence.

In one aspect, a mouse comprising in its germline a non-mouse nucleicacid sequence that encodes an immunoglobulin protein is provided,wherein the non-mouse immunoglobulin sequence comprises an insertion ofa mouse ADAM6 gene or homolog or ortholog or functional fragmentthereof. In one embodiment, the non-mouse immunoglobulin sequencecomprises a human immunoglobulin sequence. In one embodiment, thesequence comprises a human immunoglobulin heavy chain sequence. In oneembodiment, the sequence comprises a human immunoglobulin light chainsequence. In one embodiment, the sequence comprises a single V_(H) genesegment, one or more D_(H) gene segments, and one or more J_(H) genesegments; in one embodiment, the sequence comprises one or more V_(L)gene segments and one or more J_(L) gene segments. In one embodiment,the single V_(H), one or more D_(H), and one or more J_(H) genesegments, or one or more V_(L) and J_(L) gene segments, are notrearranged. In one embodiment, the single V_(H), one or more D_(H), andone or more J_(H) gene segments, or one or more V_(L) and J_(L) genesegments, are rearranged. In one embodiment, following rearrangement ofthe single V_(H), one or more D_(H), and one or more J_(H) genesegments, or one or more V_(L) and J₁ gene segments, the mouse comprisesin its genome at least one nucleic acid sequence encoding a mouse ADAM6gene or homolog or ortholog or functional fragment thereof. In oneembodiment, following rearrangement the mouse comprises in its genome atleast two nucleic acid sequences encoding a mouse ADAM6 gene or homologor ortholog or functional fragment thereof. In one embodiment, followingrearrangement the mouse comprises in its genome at least one nucleicacid sequence encoding a mouse ADAM6 gene or homolog or ortholog orfunctional fragment thereof. In one embodiment, the mouse comprises theADAM6 gene or homolog or ortholog or functional fragment thereof in a Bcell. In one embodiment, the mouse comprises the ADAM6 gene or homologor ortholog or functional fragment thereof in a non-B cell.

In one aspect, mice are provided that express a human immunoglobulinheavy chain variable region or functional fragment thereof from anendogenous mouse immunoglobulin heavy chain locus, wherein the micecomprise an ADAM6 activity that is functional in a male mouse. In oneembodiment, the human immunoglobulin heavy chain variable regioncomprises a polymorphic human V_(H) gene segment. In one embodiment, thehuman immunoglobulin heavy chain variable region comprises a humanV_(H)1-69 gene segment. In one embodiment, the human immunoglobulinheavy chain variable region comprises a human V_(H)1-2 gene segment.

In one embodiment, the male mice comprise a single unmodified endogenousADAM6 allele or ortholog of homolog or functional fragment thereof at anendogenous ADAM6 locus.

In one embodiment, the male mice comprise an ectopic mouse ADAM6sequence or homolog or ortholog or functional fragment thereof thatencodes a protein that confers ADAM6 function.

In one embodiment, the male mice comprise an ADAM6 sequence or homologor ortholog or functional fragment thereof at a location in the mousegenome that approximates the location of the endogenous mouse ADAM6allele, e.g., 3′ of a V gene segment sequence and 5′ of an initial Dgene segment. In a specific embodiment, the male mice comprise an ADAM6sequence or homolog or ortholog or functional fragment thereof 3′ of ahuman V_(H) gene segment and 5′ of a human D_(H) gene segment. Inanother specific embodiment, the male mice comprise an ADAM6 sequence orhomolog or ortholog or functional fragment thereof 5′ of a human V_(H)gene segment. In another specific embodiment, the male mice comprise anADAM6 sequence or homolog or ortholog or functional fragment thereof 5′of a chimeric heavy chain locus comprising a single human V_(H) genesegment, one or more D_(H) gene segments, and one or more J_(H) genesegments. In one embodiment, the chimeric heavy chain locus comprises ahuman V_(H)1-69 gene segment, 27 human D_(H) gene segments, and sixhuman J_(H) gene segments. In one embodiment, the chimeric heavy chainlocus comprises a human V_(H)1-2 gene segment, 27 human D_(H) genesegments, and six human J_(H) gene segments.

In one embodiment, the male mice comprise an ADAM6 sequence or homologor ortholog or functional fragment thereof flanked upstream, downstream,or upstream and downstream (with respect to the direction oftranscription of the ADAM6 sequence) of a nucleic acid sequence encodingan immunoglobulin variable gene segment or an immunoglobulin diversitygene segment. In a specific embodiment, the immunoglobulin variable genesegment is a human gene segment. In one embodiment, the immunoglobulinvariable gene segment is a human gene segment, and the sequence encodingthe mouse ADAM6 or ortholog or homolog or fragment thereof functional ina mouse is between human V_(H) gene segments; in one embodiment, themouse comprises one human V_(H) gene segment, and the sequence is at aposition 5′ of the V_(H) gene segment; in one embodiment, the sequenceis at a position 3′ of the V_(H) gene segment; in one embodiment, thesequence is at a position between the V_(H) gene segment and the firstD_(H) gene segment. In a specific embodiment, the D_(H) gene segment isthe first D_(H) gene segment. In one embodiment, the mouse comprises twoV_(H) gene segments, and the sequence is at a position between the twoV_(H) gene segments; in one embodiment, the sequence is at a positionbetween a V_(H) gene segment and a D_(H) gene segment. In a specificembodiment, the D_(H) gene segment is the first D_(H) gene segment.

In one embodiment, the mate mice comprise an ADAM6 sequence or homologor ortholog or functional fragment thereof that is located at a positionin an endogenous immunoglobulin locus that is the same or substantiallythe same as in a wild type male mouse. In a specific embodiment, theendogenous locus is incapable of encoding the heavy chain of anantibody. In a specific embodiment, the endogenous locus is positionedat a location in the genome of the male mouse that renders it incapableof encoding the heavy chain of an antibody. In various embodiments, themale mice comprise an ADAM6 sequence located on the same chromosome ashuman immunoglobulin gene segments and the ADAM6 sequence encodes afunctional ADAM6 protein.

In one aspect, a male mouse is provided that comprises a nonfunctionalendogenous ADAM6 gene, or a deletion of an endogenous ADAM6 gene, in itsgermline; wherein sperm cells of the mouse are capable of transiting anoviduct of a female mouse and fertilizing an egg. In one embodiment, themice comprise an extrachromosomal copy of a mouse ADAM6 gene or orthologor homolog or functional fragment thereof that is functional in a malemouse. In one embodiment, the mice comprise an ectopic mouse ADAM6 geneor ortholog or homolog or functional fragment thereof that is functionalin a male mouse.

In one aspect, mice are provided that comprise a genetic modificationthat reduces endogenous mouse ADAM6 function, wherein the mousecomprises at least some ADAM6 functionality provided either by anendogenous unmodified allele that is functional in whole or in part(e.g., a heterozygote), or by expression from an ectopic sequence thatencodes an ADAM6 or an ortholog or homolog or functional fragmentthereof that is functional in a male mouse.

In one embodiment, the mice comprise ADAM6 function sufficient to conferupon male mice the ability to generate offspring by mating, as comparedwith male mice that lack a functional ADAM6. In one embodiment, theADAM6 function is conferred by the presence of an ectopic nucleotidesequence that encodes a mouse ADAM6 or a homolog or ortholog orfunctional fragment thereof. In one embodiment, the ADAM6 function isconferred by an endogenous ADAM6 gene present in an endogenousimmunoglobulin locus, wherein the endogenous immunoglobulin locus isincapable of encoding the heavy chain of an antibody. ADAM6 homologs ororthologs or fragments thereof that are functional in a male mouseinclude those that restore, in whole or in part, the loss of ability togenerate offspring observed in a male mouse that lacks sufficientendogenous mouse ADAM6 activity, e.g., the loss in ability observed inan ADAM6 knockout mouse. In this sense ADAM6 knockout mice include micethat comprise an endogenous locus or fragment thereof, but that is notfunctional, i.e., that does not express ADAM6 (ADAM6a and/or ADAM6b) atall, or that expresses ADAM6 (ADAM6a and/or ADAM6b) at a level that isinsufficient to support an essentially normal ability to generateoffspring of a wild-type male mouse. The loss of function can be due,e.g., to a modification in a structural gene of the locus (i.e., in anADAM6a or ADAM6b coding region) or in a regulatory region of the locus(e.g., in a sequence 5′ to the ADAM6a gene, or 3′ of the ADAM6a orADAM6b coding region, wherein the sequence controls, in whole or inpart, transcription of an ADAM6 gene, expression of an ADAM6 RNA, orexpression of an ADAM6 protein). In various embodiments, orthologs orhomologs or fragments thereof that are functional in a male mouse arethose that enable a sperm of a male mouse (or a majority of sperm cellsin the ejaculate of a male mouse) to transit a mouse oviduct andfertilize a mouse ovum.

In one embodiment, male mice that express the human immunoglobulinvariable region or functional fragment thereof comprise sufficient ADAM6activity to confer upon the male mice the ability to generate offspringby mating with female mice and, in one embodiment, the male mice exhibitan ability to generate offspring when mating with female mice that is inone embodiment at least 25%, in one embodiment, at least 30%, in oneembodiment at least 40%, in one embodiment at least 50%, in oneembodiment at least 60%, in one embodiment at least 70%, in oneembodiment at least 80%, in one embodiment at least 90%, and in oneembodiment about the same as, that of mice with one or two endogenousunmodified ADAM6 alleles.

In one embodiment male mice express sufficient ADAM6 (or an ortholog orhomolog or functional fragment thereof) to enable a sperm cell from themale mice to traverse a female mouse oviduct and fertilize a mouse egg.

In one embodiment, the ADAM6 functionality is conferred by a nucleicacid sequence that is contiguous with a mouse chromosomal sequence(e.g., the nucleic acid is randomly integrated into a mouse chromosome;or placed at a specific location, e.g., by targeting the nucleic acid toa specific location, e.g., by site-specific recombinase-mediated (e.g.,Cre-mediated) insertion or homologous recombination). In one embodiment,the ADAM6 sequence is present on a nucleic acid that is distinct from achromosome of the mouse (e.g., the ADAM6 sequence is present on anepisome, i.e., extrachromosomally, e.g., in an expression construct, avector, a YAC, a transchromosome, etc.).

In one aspect, genetically modified mice and cells are provided thatcomprise a modification of an endogenous immunoglobulin heavy chainlocus, wherein the mice express at least a portion of an immunoglobulinheavy chain sequence, e.g., at least a portion of a human sequence,wherein the mice comprise an ADAM6 activity that is functional in a malemouse. In one embodiment, the modification reduces or eradicates ADAM6activity of the mouse. In one embodiment, the mouse is modified suchthat both alleles that encode ADAM6 activity are either absent orexpress an ADAM6 that does not substantially function to support normalmating in a male mouse. In one embodiment, the mouse further comprisesan ectopic nucleic acid sequence encoding a mouse ADAM6 or ortholog orhomolog or functional fragment thereof. In one embodiment, themodification maintains ADAM6 activity of the mouse and renders anendogenous immunoglobulin heavy chain locus incapable of encoding aheavy chain of an antibody. In a specific embodiment, the modificationincludes chromosomal inversions and or translocations that render theendogenous immunoglobulin heavy chain locus incapable of encoding aheavy chain of an antibody.

In one aspect, genetically modified mice and cells are provided thatcomprise a modification of an endogenous immunoglobulin heavy chainlocus, wherein the modification reduces or eliminates ADAM6 activityexpressed from an ADAM6 sequence of the locus, and wherein the micecomprise an ADAM6 protein or ortholog or homolog or functional fragmentthereof. In various embodiments, the ADAM6 protein or fragment thereofis encoded by an ectopic ADAM6 sequence. In various embodiments, theADAM6 protein or fragment thereof is expressed from an endogenous ADAM6allele. In various embodiments, the mouse comprises a firstimmunoglobulin heavy chain allele comprises a first modification thatreduces or eliminates expression of a functional ADAM6 from the firstimmunoglobulin heavy chain allele, and the mouse comprises a secondimmunoglobulin heavy chain allele that comprises a second modificationthat does not substantially reduce or does not eliminate expression of afunctional ADAM6 from the second immunoglobulin heavy chain allele.

In one embodiment, the second modification is located 3′ (with respectto the transcriptional directionality of the mouse V gene segment) of afinal mouse V gene segment and located 5′ (with respect to thetranscriptional directionality of the constant sequence) of a mouse (orchimeric human/mouse) immunoglobulin heavy chain constant gene orfragment thereof (e.g., a nucleic acid sequence encoding a human and/ormouse: C_(H)1 and/or hinge and/or C_(H)2 and/or C_(H)3).

In one embodiment, the modification is at a first immunoglobulin heavychain allele at a first locus that encodes a first ADAM6 allele, and theADAM6 function results from expression of an endogenous ADAM6 at asecond immunoglobulin heavy chain allele at a second locus that encodesa functional ADAM6, wherein the second immunoglobulin heavy chain allelecomprises at least one modification of a V, D, and/or J gene segment. Ina specific embodiment, the at least one modification of the V, D, and orJ gene segment is a deletion, a replacement with a single human V_(H),one or more D_(H), and/or one or more J_(H) gene segments, a replacementwith a camelid V_(H) (or V_(HH)), D_(H), and/or J_(H) gene segment, areplacement with a humanized or camelized V_(H) (or V_(HH)), D_(H),and/or J_(H) gene segment, a replacement of a heavy chain sequence witha light chain sequence, and a combination thereof. In one embodiment,the at least one modification is the deletion of one or more V_(H),D_(H), and/or J_(H) gene segments and a replacement with one or moreV_(L) and/or J_(L) gene segments (e.g., a human V_(L) and/or J_(L) genesegment) at the heavy chain locus.

In one embodiment, the modification is at a first immunoglobulin heavychain allele at a first locus and a second immunoglobulin heavy chainallele at a second locus, and the ADAM6 function results from expressionof an ectopic ADAM6 at a non-immunoglobulin locus in the germline of themouse. In a specific embodiment, the non-immunoglobulin locus is theROSA26 locus. In a specific embodiment, the non-immunoglobulin locus istranscriptionally active in reproductive tissue.

In one embodiment, the modification is at a first immunoglobulin heavychain allele at a first locus and a second immunoglobulin heavy chainallele at a second locus, and the ADAM6 function results from expressionof an ectopic ADAM6 at the first immunoglobulin heavy chain allele. Inone embodiment, the modification is at a first immunoglobulin heavychain allele at a first locus and a second immunoglobulin heavy chainallele at a second locus, and the ADAM6 function results from expressionof an ectopic ADAM6 at the second immunoglobulin heavy chain allele.

In one aspect, a mouse comprising a heterozygous or a homozygousknockout of ADAM6 is provided. In one embodiment, the mouse furthercomprises a modified immunoglobulin sequence that is a human or ahumanized immunoglobulin sequence, or a camelid or camelized human ormouse immunoglobulin sequence. In one embodiment, the modifiedimmunoglobulin sequence is present at the endogenous mouse heavy chainimmunoglobulin locus. In one embodiment, the modified immunoglobulinsequence comprises a human heavy chain variable gene sequence at anendogenous mouse immunoglobulin heavy chain locus. In one embodiment,the human heavy chain variable gene sequence replaces an endogenousmouse heavy chain variable gene sequence at the endogenous mouseimmunoglobulin heavy chain locus.

In one aspect, a mouse incapable of expressing a functional endogenousmouse ADAM6 from an endogenous mouse ADAM6 locus is provided. In oneembodiment, the mouse comprises an ectopic nucleic acid sequence thatencodes an ADAM6, or functional fragment thereof, that is functional inthe mouse. In a specific embodiment, the ectopic nucleic acid sequenceencodes a protein that rescues a loss in the ability to generateoffspring exhibited by a male mouse that is homozygous for an ADAM6knockout. In a specific embodiment, the ectopic nucleic acid sequenceencodes a mouse ADAM6 protein.

In one aspect, a mouse is provided that lacks a functional endogenousADAM6 locus, and that comprises an ectopic nucleic acid sequence thatconfers upon the mouse ADAM6 function. In one embodiment, the nucleicacid sequence comprises an endogenous mouse ADAM6 sequence or functionalfragment thereof. In one embodiment, the endogenous mouse ADAM6 sequencecomprises ADAM6a- and ADAM6b-encoding sequence located in a wild-typemouse between the 3′-most mouse immunoglobulin heavy chain V genesegment (V_(H)) and the 5′-most mouse immunoglobulin heavy chain D genesegment (D_(H)).

In one embodiment, the nucleic acid sequence comprises a sequenceencoding mouse ADAM6a or functional fragment thereof and/or a sequenceencoding mouse ADAM6b or functional fragment thereof, wherein the ADAM6aand/or ADAM6b or functional fragment(s) thereof is operably linked to apromoter. In one embodiment, the promoter is a human promoter. In oneembodiment, the promoter is the mouse ADAM6 promoter. In a specificembodiment, the ADAM6 promoter comprises sequence located between thefirst codon of the first ADAMS gene closest to the mouse 5′-most D_(H)gene segment and the recombination signal sequence of the 5′-most D_(H)gene segment, wherein 5′ is indicated with respect to direction oftranscription of the mouse immunoglobulin genes. In one embodiment, thepromoter is a viral promoter. In a specific embodiment, the viralpromoter is a cytomegalovirus (CMV) promoter. In one embodiment, thepromoter is a ubiquitin promoter.

In one embodiment, the promoter is an inducible promoter. In oneembodiment, the inducible promoter regulates expression innon-reproductive tissues. In one embodiment, the inducible promoterregulates expression in reproductive tissues. In a specific embodiment,the expression of the mouse ADAM6a and/or ADAM6b sequences or functionalfragments(s) thereof is developmentally regulated by the induciblepromoter in reproductive tissues.

In one embodiment, the mouse ADAM6a and/or ADAM6b are selected from theADAM6a of SEQ ID NO: 1 and/or ADAM6b of sequence SEQ ID NO: 2.

In one embodiment, the mouse ADAM6 promoter is a promoter of SEQ ID NO:3. In a specific embodiment, the mouse ADAM6 promoter comprises thenucleic acid sequence of SEQ ID NO: 3 directly upstream (with respect tothe direction of transcription of ADAM6a) of the first codon of ADAM6aand extending to the end of SEQ ID NO: 3 upstream of the ADAM6 codingregion. In another specific embodiment, the ADAM6 promoter is a fragmentextending from within about 5 to about 20 nucleotides upstream of thestart codon of ADAM6a to about 0.5 kb, 1 kb, 2 kb, or 3 kb or moreupstream of the start codon of ADAM6a.

In one embodiment, the mouse ADAM6 promoter is a promoter of SEQ ID NO:73. In a specific embodiment, the mouse ADAM6 promoter comprises thenucleic acid sequence of SEQ ID NO: 73 directly upstream (with respectto the direction of transcription of ADAM6a) of the first codon ofADAM6a and extending to the end of SEQ ID NO: 73 upstream of the ADAM6coding region. In another specific embodiment, the ADAM6 promoter is afragment extending from within about 5 to about 20 nucleotides upstreamof the start codon of ADAM6a to about 0.5 kb, 1 kb, 2 kb, or 3 kb ormore upstream of the start codon of ADAM6a.

In one embodiment, the mouse ADAM6 promoter is a promoter of SEQ ID NO:77. In a specific embodiment, the mouse ADAM6 promoter comprises thenucleic acid sequence of SEQ ID NO: 77 directly upstream (with respectto the direction of transcription of ADAM6a) of the first codon ofADAM6a and extending to the end of SEQ ID NO: 77 upstream of the ADAM6coding region. In another specific embodiment, the ADAM6 promoter is afragment extending from within about 5 to about 20 nucleotides upstreamof the start codon of ADAM6a to about 0.5 kb, 1 kb, 2 kb, or 3 kb ormore upstream of the start codon of ADAM6a.

In one embodiment, the nucleic acid sequence comprises SEQ ID NO: 3 or afragment thereof that when placed into a mouse that is infertile or thathas low fertility due to a lack of ADAM6, improves fertility or restoresfertility to about a wild-type fertility. In one embodiment, SEQ ID NO:3 or a fragment thereof confers upon a male mouse the ability to producea sperm cell that is capable of traversing a female mouse oviduct inorder to fertilize a mouse egg.

In one embodiment, the nucleic acid sequence comprises SEQ ID NO: 73 ora fragment thereof that when placed into a mouse that is infertile orthat has low fertility due to a lack of ADAMS, improves fertility orrestores fertility to about a wild-type fertility. In one embodiment,SEQ ID NO: 73 or a fragment thereof confers upon a male mouse theability to produce a sperm cell that is capable of traversing a femalemouse oviduct in order to fertilize a mouse egg.

In one embodiment, the nucleic acid sequence comprises SEQ ID NO: 77 ora fragment thereof that when placed into a mouse that is infertile orthat has low fertility due to a lack of ADAM6, improves fertility orrestores fertility to about a wild-type fertility. In one embodiment,SEQ ID NO: 77 or a fragment thereof confers upon a male mouse theability to produce a sperm cell that is capable of traversing a femalemouse oviduct in order to fertilize a mouse egg.

In one aspect, a mouse is provided that comprises a deletion of anendogenous nucleotide sequence that encodes an ADAM6 protein, areplacement of an endogenous mouse V_(H) gene segment with a human V_(H)gene segment, and an ectopic nucleotide sequence that encodes a mouseADAM6 protein or ortholog or homolog or fragment thereof that isfunctional in a male mouse.

In one embodiment, the mouse comprises an immunoglobulin heavy chainlocus that comprises a deletion of an endogenous immunoglobulin locusnucleotide sequence that comprises an endogenous ADAM6 gene, comprises anucleotide sequence encoding one or more human immunoglobulin genesegments, and wherein the ectopic nucleotide sequence encoding the mouseADAM6 protein is within or directly adjacent to the nucleotide sequenceencoding the one or more human immunoglobulin gene segments.

In one embodiment, the mouse comprises a replacement of all orsubstantially all endogenous V_(H) gene segments with a nucleotidesequence encoding a single human V_(H) gene segment, and the ectopicnucleotide sequence encoding the mouse ADAM6 protein is within, ordirectly adjacent to, the nucleotide sequence encoding the single humanV_(H) gene segment. In one embodiment, the mouse further comprises areplacement of one or more endogenous D_(H) gene segments with one ormore human D_(H) gene segments at the endogenous D_(H) gene locus. Inone embodiment, the mouse further comprises a replacement of one or moreendogenous J_(H) gene segments with one or more human J_(H) genesegments at the endogenous J_(H) gene locus. In one embodiment, themouse comprises a replacement of all or substantially all endogenousV_(H), D_(H), and J_(H) gene segments and a replacement at theendogenous V_(H), D_(H), and J_(H) gene loci with a single human V_(H),one or more human D_(H), and one or more human J_(H) gene segments,wherein the mouse comprises an ectopic sequence encoding a mouse ADAM6protein. In a specific embodiment, the ectopic sequence encoding themouse ADAM6 protein is placed upstream or 5′ of the single human V_(H)gene segment. In another specific embodiment, the ectopic sequenceencoding the mouse ADAM6 protein is placed downstream or 3′ of thesingle human V_(H) gene segment. In another specific embodiment, theectopic sequence encoding the mouse ADAM6 protein is placed between thesingle human V_(H) gene segment and the first human D_(H) gene segmentpresent. In another specific embodiment, the mouse comprises a deletionof all or substantially all mouse V_(H) gene segments, and a replacementwith a single human V_(H) gene segment, and the ectopic nucleotidesequence encoding the mouse ADAM6 protein is placed downstream of humangene segment V_(H)1-69 and upstream of human gene segment D_(H)1-1. Inanother specific embodiment, the mouse comprises a deletion of all orsubstantially all mouse V_(H) gene segments, and a replacement with asingle human V_(H) gene segment, and the ectopic nucleotide sequenceencoding the mouse ADAM6 protein is placed downstream of human genesegment V_(H)1-2 and upstream of human gene segment D_(H)1-1.

In a specific embodiment, the mouse comprises a replacement of all orsubstantially all endogenous V_(H) gene segments with a nucleotidesequence encoding a single V_(H) gene segments, and the ectopicnucleotide sequence encoding the mouse ADAM6 protein is within, ordirectly adjacent to, the nucleotide sequence encoding the single humanV_(H) gene segment.

In one embodiment, the ectopic nucleotide sequence that encodes themouse ADAM6 protein is present on a transgene in the genome of themouse. In one embodiment, the ectopic nucleotide sequence that encodesthe mouse ADAM6 protein is present extrachromosomally in the mouse.

In one aspect, a mouse is provided that comprises a modification of anendogenous immunoglobulin heavy chain locus, wherein the mouse expressesa B cell that comprises a rearranged immunoglobulin sequence operablylinked to a heavy chain constant region gene sequence, and the B cellcomprises in its genome (e.g., on a B cell chromosome) a gene encodingan ADAM6 or ortholog or homolog or fragment thereof that is functionalin a male mouse. In one embodiment, the rearranged immunoglobulinsequence operably linked to the heavy chain constant region genesequence comprises a human heavy chain V, D, and/or J sequence; a mouseheavy chain V, D, and/or J sequence; a human or mouse light chain Vand/or J sequence. In one embodiment, the heavy chain constant regiongene sequence comprises a human or a mouse heavy chain sequence selectedfrom the group consisting of a C_(H)1, a hinge, a C_(H)2, a C_(H)3, anda combination thereof.

In one aspect, a mouse is provided that comprises a functionallysilenced endogenous immunoglobulin heavy chain locus, wherein ADAM6function is maintained in the mouse, and further comprises an insertionof one or more human immunoglobulin gene segments, wherein the one ormore human immunoglobulin gene segments include a single human V_(H)gene segment, one or more human D_(H) gene segments, and one or morehuman J_(H) gene segments. In one embodiment, the one or more humanimmunoglobulin gene segments includes a human V_(H)1-69 gene segment, 27human D_(H) gene segments, and six human J_(H) gene segments. In oneembodiment, the one or more human immunoglobulin gene segments include ahuman V_(H)1-2 gene segment, 27 human D_(H) gene segments, and six humanJ_(H) gene segments.

In one aspect, a genetically modified mouse is provided, wherein themouse comprises a functionally silenced immunoglobulin light chain gene,and further comprises a replacement of one or more endogenousimmunoglobulin heavy chain variable region gene segments with a singlehuman immunoglobulin heavy chain variable region gene segment, whereinthe mouse lacks a functional endogenous ADAM6 locus, and wherein themouse comprises an ectopic nucleotide sequence that expresses a mouseADAM6 protein or an ortholog or homolog or fragment thereof that isfunctional in a male mouse.

In one aspect, a mouse is provided that lacks a functional endogenousmouse ADAM6 locus or sequence and that comprises an ectopic nucleotidesequence encoding a mouse ADAM6 locus or functional fragment of a mouseADAM6 locus or sequence, wherein the mouse is capable of mating with amouse of the opposite sex to produce a progeny that comprises theectopic ADAM6 locus or sequence. In one embodiment, the mouse is male.In one embodiment, the mouse is female.

In one aspect, a genetically modified mouse is provided, wherein themouse comprises a human immunoglobulin heavy chain variable region genesegment at an endogenous mouse immunoglobulin heavy chain variableregion gene locus, the mouse lacks an endogenous functional ADAM6sequence at the endogenous mouse immunoglobulin heavy chain variableregion gene locus, and wherein the mouse comprises an ectopic nucleotidesequence that expresses a mouse ADAM6 protein or an ortholog or homologor fragment thereof that is functional in a male mouse.

In one embodiment, the ectopic nucleotide sequence that expresses themouse ADAM6 protein is extrachromosomal. In one embodiment, the ectopicnucleotide sequence that expresses the mouse ADAM6 protein is integratedat one or more loci in a genome of the mouse. In a specific embodiment,the one or more loci include an immunoglobulin locus.

In one aspect, a mouse is provided that expresses an immunoglobulinheavy chain sequence from a modified endogenous mouse immunoglobulinheavy chain locus, wherein the heavy chain is derived from a human Vgene segment, a D gene segment, and a J gene segment, wherein the mousecomprises an ADAM6 activity that is functional in the mouse.

In one embodiment, the mouse comprises a single human V gene segment, aplurality of D gene segments, and a plurality of J gene segments. In oneembodiment, the D gene segments are human D gene segments. In oneembodiment, the J gene segments are human J gene segments. In oneembodiment, the mouse further comprises a humanized heavy chain constantregion sequence, wherein the humanization comprises replacement of asequence selected from a C_(H)1, hinge, C_(H)2, C_(H)3, and acombination thereof. In a specific embodiment, the heavy chain isderived from the human V gene segment, a human D gene segment, a human Jgene segment, a human C_(H)1 sequence, a human or mouse hinge sequence,a mouse C_(H)2 sequence, and a mouse C_(H)3 sequence. In anotherspecific embodiment, the mouse further comprises a human light chainconstant sequence.

In one embodiment, the mouse comprises an ADAM6 gene that is flanked 5′and 3′ by endogenous immunoglobulin heavy chain gene segments. In aspecific embodiment, the endogenous immunoglobulin heavy chain genesegments are incapable of encoding a heavy chain of an antibody. In aspecific embodiment, the ADAM6 gene of the mouse is at a position thatis the same as in a wild-type mouse and the endogenous immunoglobulinheavy chain variable gene loci of the mouse are incapable of rearrangingto encode a heavy chain of an antibody.

In one embodiment, the V gene segment is flanked 5′ (with respect totranscriptional direction of the V gene segment) by a sequence encodingan ADAM6 activity that is functional in the mouse.

In one embodiment, the V gene segment is flanked 3′ (with respect totranscriptional direction of the V gene segment) by a sequence encodingan ADAM6 activity that is functional in the mouse.

In one embodiment, the D gene segment is flanked 5′ (with respect totranscriptional direction of the D gene segment) by a sequence encodingan ADAM6 activity that is functional in the mouse.

In one embodiment, the J gene segment is flanked 5′ (with respect totranscriptional direction of the J gene segment) by a sequence encodingan ADAM6 activity that is functional in the mouse.

In one embodiment, the ADAM6 activity that is functional in the mouseresults from expression of a nucleotide sequence located 5′ of the5′-most D gene segment and 3′ of the single V gene segment (with respectto the direction of transcription of the V gene segment) of the modifiedendogenous mouse heavy chain immunoglobulin locus.

In one embodiment, the ADAM6 activity that is functional in the mouseresults from expression of a nucleotide sequence located 5′ of the5′-most J gene segment and 3′ of the 3′-most D gene segment (withrespect to the direction of transcription of the D gene segment) of themodified endogenous mouse heavy chain immunoglobulin locus.

In one embodiment, the ADAM6 activity that is functional in the mouseresults from expression of a nucleotide sequence located 5′ of thesingle human V gene segment (with respect to the direction oftranscription of the V gene segment) of the modified endogenous mouseheavy chain immunoglobulin locus.

In one embodiment, the nucleotide sequence comprises a sequence selectedfrom a mouse ADAM6b sequence or functional fragment thereof, a mouseADAM6a sequence or functional fragment thereof, and a combinationthereof.

In one embodiment, the nucleotide sequence positioned upstream (5′) ordownstream (3′) of the single human V gene segment is placed in oppositetranscription orientation with respect to the human V gene segment. In aspecific embodiment, nucleotide sequence encodes, from 5′ to 3′ withrespect to the direction of transcription of ADAM6 genes, and ADAM6asequence followed by an ADAM6b sequence.

In one embodiment, the mouse comprises a single human V_(H) gene segmentjuxtaposed or contiguous with a mouse ADAM6 sequence or functionalfragment thereof.

In one embodiment, the mouse comprises a human V_(H)1-69 gene segmentjuxtaposed or contiguous with a mouse ADAM6 sequence or functionalfragment thereof.

In one embodiment, the mouse comprises a human V_(H)1-2 gene segmentjuxtaposed or contiguous with a mouse ADAM6 sequence or functionalfragment thereof.

In one embodiment, the mouse comprises a single human V_(H) genesegment, and the mouse ADAM6 sequence or functional fragment thereof isjuxtaposed or contiguous with endogenous immunoglobulin heavy chain genesegments, wherein the endogenous immunoglobulin heavy chain genesegments are incapable of rearranging to encode a heavy chain of anantibody.

In one embodiment, the sequence encoding the ADAM6 activity that isfunctional in the mouse is a mouse ADAM6 sequence or functional fragmentthereof.

In one aspect, a mouse is provided that comprises a nucleic acidsequence encoding a mouse ADAM6 (or homolog or ortholog or functionalfragment thereof) in a DNA-bearing cell of non-rearranged B celllineage, but does not comprise the nucleic acid sequence encoding themouse ADAM6 (or homolog or ortholog or functional fragment thereof) in aB cell that comprise rearranged immunoglobulin loci, wherein the nucleicacid sequence encoding the mouse ADAM6 (or homolog or ortholog orfunctional fragment thereof) occurs in the genome at a position that isdifferent from a position in which a mouse ADAM6 gene appears in awild-type mouse. In one embodiment, the nucleic acid sequence encodingthe mouse ADAM6 (or homolog or ortholog or functional fragment thereof)is present in all or substantially all DNA-bearing cells that are not ofrearranged B cell lineage; in one embodiment, the nucleic acid sequenceis present in germline cells of the mouse, but not in a chromosome of arearranged B cell.

In one aspect, a mouse is provided that comprises a nucleic acidsequence encoding a mouse ADAM6 (or homolog or ortholog or functionalfragment thereof) in all or substantially all DNA-bearing cells,including B cells that comprise rearranged immunoglobulin loci, whereinthe nucleic acid sequence encoding the mouse ADAM6 (or homolog orortholog or functional fragment thereof) occurs in the genome at aposition that is different from a position in which a mouse ADAM6 geneappears in a wild-type mouse. In one embodiment, the nucleic acidsequence encoding the mouse ADAM6 (or homolog or ortholog or functionalfragment thereof) is on a nucleic acid that is contiguous with therearranged immunoglobulin locus. In one embodiment, the nucleic acidthat is contiguous with the rearranged immunoglobulin locus is achromosome. In one embodiment, the chromosome is a chromosome that isfound in a wild-type mouse and the chromosome comprises a modificationof a mouse immunoglobulin locus.

In one aspect, a genetically modified mouse is provided, wherein themouse comprises a B cell that comprises in its genome an ADAM6 sequenceor ortholog or homolog thereof. In one embodiment, the ADAM6 sequence orortholog or homolog thereof is at an immunoglobulin heavy chain locus.In a specific embodiment, the heavy chain locus comprises endogenousimmunoglobulin heavy chain gene segments that are incapable ofrearranging to encode the heavy chain of an antibody. In one embodiment,the ADAM6 sequence or ortholog or homolog thereof is at a locus that isnot an immunoglobulin locus. In one embodiment, the ADAM6 sequence is ona transgene driven by a heterologous promoter. In a specific embodiment,the heterologous promoter is a non-immunoglobulin promoter. In aspecific embodiment, B cell expresses an ADAM6 protein or ortholog orhomolog thereof.

In one embodiment, 90% or more of the B cells of the mouse comprise agene encoding an ADAM6 protein or an ortholog thereof or a homologthereof or a fragment thereof that is functional in the mouse. In aspecific embodiment, the mouse is a male mouse.

In one embodiment, the B cell genome comprises a first allele and asecond allele comprising the ADAM6 sequence or ortholog or homologthereof. In one embodiment, the B cell genome comprises a first allelebut not a second allele comprising the ADAM6 sequence or ortholog orhomolog thereof.

In one aspect, a mouse is provided that comprises a modification at oneor more endogenous immunoglobulin heavy chain alleles, wherein themodification maintains one or more endogenous ADAM6 alleles.

In one embodiment, the modification renders the mouse incapable ofexpressing a functional heavy chain that comprises rearranged endogenousheavy chain gene segments from at least one heavy chain allele andmaintains an endogenous ADAM6 allele located within the at least oneendogenous immunoglobulin heavy chain allele.

In one embodiment, the mice are incapable of expressing a functionalheavy chain that comprises rearranged endogenous heavy chain genesegments from at least one of the endogenous immunoglobulin heavy chainalleles, and the mice express and ADAM6 protein from an endogenous ADAM6allele. In a specific embodiment, the mice are incapable of expressing afunctional heavy chain that comprises rearranged endogenous heavy chaingene segments from two endogenous immunoglobulin heavy chain alleles,and the mice express an ADAM6 protein from one or more endogenous ADAM6alleles.

In one embodiment, the mice are incapable of expressing a functionalheavy chain from each endogenous heavy chain allele, and the micecomprise an functional ADAM6 allele located within 1, 2, 3, 4, 5, 10,20, 30, 40, 50, 60, 70, 80, 90, 100, 110, or 120 or more Mbp upstream(with respect to the direction of transcription of the mouse heavy chainlocus) of a mouse immunoglobulin heavy chain constant region sequence.In a specific embodiment, the functional ADAM6 allele is at theendogenous immunoglobulin heavy chain locus (e.g., in an intergenic V-Dregion, between two V gene segments, between a V and a D gene segment,between a D and a J gene segment, etc.). In a specific embodiment, thefunctional ADAM6 allele is located within a 90 to 100 kb intergenicsequence between the final mouse V gene segment and the first mouse Dgene segment.

In one aspect, a mouse is provided that comprises a modification at oneor more endogenous ADAM6 alleles.

In one embodiment, the modification renders the mouse incapable ofexpressing a functional ADAM6 protein from at least one of the one ormore endogenous ADAM6 alleles. In a specific embodiment, the mouse isincapable of expressing a functional ADAM6 protein from each of theendogenous ADAM6 alleles.

In one embodiment, the mice are incapable of expressing a functionalADAM6 protein from each endogenous ADAM6 allele, and the mice comprisean ectopic ADAM6 sequence.

In one embodiment, the mice are incapable of expressing a functionalADAM6 protein from each endogenous ADAM6 allele, and the mice comprisean ectopic ADAM6 sequence located within 1, 2, 3, 4, 5, 10, 20, 30, 40,50, 60, 70, 80, 90, 100, 110, or 120 or more kb upstream (with respectto the direction of transcription of the mouse heavy chain locus) of amouse immunoglobulin heavy chain constant region sequence. In a specificembodiment, the ectopic ADAM6 sequence is at the endogenousimmunoglobulin heavy chain locus (e.g., in an intergenic V-D region,between two V gene segments, between a V and a D gene segment, between aD and a J gene segment, etc.). In a specific embodiment, the ectopicADAM6 sequence is located within a 90 to 100 kb intergenic sequencebetween the final mouse V gene segment and the first mouse D genesegment. In another specific embodiment, the endogenous 90 to 100 kbintergenic V-D sequence is removed, and the ectopic ADAM6 sequence isplaced between a single human V gene segment and a first human D genesegment. In another specific embodiment, the endogenous 90 to 100 kbintergenic V-D sequence is removed, and the ectopic ADAM6 sequence isplaced 5′ or upstream of the single human V gene segment.

In one aspect, an infertile male mouse is provided, wherein the mousecomprises a deletion of two or more endogenous ADAM6 alleles. In oneaspect, a female mouse is provided that is a carrier of a maleinfertility trait, wherein the female mouse comprises in its germline anonfunctional ADAM6 allele or a knockout of an endogenous ADAM6 allele.

In one aspect, a mouse comprising an endogenous immunoglobulin heavychain V, D, and or J gene segment that are incapable of rearranging toencode an heavy chain of an antibody is provided, wherein the majorityof the B cells of the mouse comprise an functional ADAM6 gene.

In one embodiment, the mouse comprises an intact endogenousimmunoglobulin heavy chain V, D, and J gene segments that are incapableof rearranging to encode a functional heavy chain of an antibody. In oneembodiment, the mouse comprises at least one and up to 89 V genesegments, at least one and up to 13 D gene segments, at least one and upto four J gene segments, and a combination thereof; wherein the at leastone and up to 89 V gene segments, at least one and up to 13 D genesegments, at least one and up to four J gene segments are incapable ofrearranging to encode a heavy chain variable region of an antibody. In aspecific embodiment, the mouse comprises a functional ADAM6 gene locatedwithin the intact endogenous immunoglobulin heavy chain V, D, and J genesegments. In one embodiment, the mouse comprises an endogenous heavychain locus that includes an endogenous ADAM6 locus, wherein theendogenous heavy chain locus comprises 89 V gene segments, 13 D genesegments, and four J gene segments, wherein the endogenous heavy chaingene segments are incapable of rearranging to encode a heavy chainvariable region of an antibody and the ADAM6 locus encodes an ADAM6protein that is functional in the mouse.

In one aspect, a mouse that lacks an endogenous immunoglobulin heavychain V, D, and J gene segment is provided, wherein a majority of the Bcells of the mouse comprise an ADAM6 sequence or ortholog or homologthereof.

In one embodiment, the mouse lacks endogenous immunoglobulin heavy chaingene segments selected from two or more V gene segments, two or more Dgene segments, two or more J gene segments, and a combination thereof.In one embodiment, the mouse lacks immunoglobulin heavy chain genesegments selected from at least one and up to 89 V gene segments, atleast one and up to 13 D gene segments, at least one and up to four Jgene segments, and a combination thereof. In one embodiment, the mouselacks a genomic DNA fragment from chromosome 12 comprising about threemegabases of the endogenous immunoglobulin heavy chain locus. In aspecific embodiment, the mouse lacks all functional endogenous heavychain V, D, and J gene segments. In a specific embodiment, the mouselacks 89 V_(H) gene segments, 13 D_(H) gene segments and four J_(H) genesegments.

In one aspect, a mouse is provided, wherein the mouse has a genome inthe germline comprising a modification of an immunoglobulin heavy chainlocus, wherein the modification to the immunoglobulin heavy chain locuscomprises the replacement of one or more mouse immunoglobulin variableregion sequences with one non-mouse immunoglobulin variable regionsequences, and wherein the mouse comprises a nucleic acid sequenceencoding a mouse ADAM6 protein. In a preferred embodiment, the D_(H) andJ_(H) sequences and at least 3, at least 10, at least 20, at least 40,at least 60, or at least 80 V sequences of the endogenous immunoglobulinheavy chain locus are replaced by non-mouse immunoglobulin heavy chainsequences. In a further preferred embodiment, the D_(H), J_(H), and allV_(H) sequences of the endogenous immunoglobulin heavy chain locus arereplaced by a single non-mouse immunoglobulin V gene segment, one ormore D gene segment, and one or more J gene segment sequences. Thenon-mouse immunoglobulin sequences can be unrearranged. In a preferredembodiment, the non-mouse immunoglobulin sequences comprise completeunrearranged D_(H) and J_(H) regions and a single unrearranged V_(H)sequence of the non-mouse species. In a further preferred embodiment,the non-mouse immunoglobulin sequences are capable of forming a completevariable region, i.e., a rearranged variable region containing V_(H),D_(H), and J_(H) segments joined together to form a sequence thatencodes a heavy chain variable region, of the non-mouse species. Thenon-mouse species can be Homo sapiens and the non-mouse immunoglobulinsequences can be human sequences.

In one aspect, a heavy chain immunoglobulin locus is provided thatcomprises a single functional human V segment. In one embodiment, thesingle functional human V segment is selected from a V_(H)1-2, V_(H)1-3,V_(H)1-8, V_(H)1-18, V_(H)1-24, V_(H)1-45, V_(H)1-46, V_(H)1-58,V_(H)1-69, V_(H)2-5, V_(H)2-26, V_(H)2-70, V_(H)3-7, V_(H)3-9,V_(H)3-11, V_(H)3-13, V_(H)3-15, V_(H)3-16, V_(H)3-20, V_(H)3-21,V_(H)3-23, V_(H)3-30, V_(H)3-30-3, V_(H)3-30-5, V_(H)3-33, V_(H)3-35,V_(H)3-38, V_(H)3-43, V_(H)3-48, V_(H)3-49, V_(H)3-53, V_(H)3-64,V_(H)3-66, V_(H)3-72, V_(H)3-73, V_(H)3-74, V_(H)4-4, V_(H)4-28,V_(H)4-30-1, V_(H)4-30-2, V_(H)4-30-4, V_(H)4-31, V_(H)4-34, V_(H)4-39,V_(H)4-59, V_(H)4-61, V_(H)5-51, V_(H)6-1, V_(H)7-4-1, and a V_(H)7-81segment. In one embodiment, the single functional human V segment is aV_(H)1-69 segment; in a specific embodiment, the single functional humanV segment is present in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13polymorphic forms found in the human population. In one embodiment, thesingle functional human V segment is a V_(H)1-2 segment; in a specificembodiment, the single functional human V segment is present in 1, 2, 3,4, or 5 polymorphic forms found in the human population.

In one embodiment, the heavy chain immunoglobulin locus is a modifiedlocus of a non-human animal. In one embodiment, the modified non-humanimmunoglobulin heavy chain locus is present in the non-human animal at aposition in the genome in which the corresponding unmodified non-humanlocus is found in the wild-type non-human animal. In one embodiment, themodified non-human immunoglobulin heavy chain locus is present on atransgene in a non-human animal.

In one embodiment, the single functional human V gene segment is aV_(H)1-69 gene segment. In one embodiment, the V_(H)1-69 gene segmentcomprises SEQ ID NO: 37. In one embodiment, the V_(H)1-69 gene segmentis derived from SEQ ID NO: 37. In one embodiment, the V_(H)1-69 genesegment is at least 80%, at least 85%, at least 90%, at least 95%, or atleast 98% identical to SEQ ID NO: 37.

In one embodiment, the single functional human V gene segment is encodedby the nucleotide sequence of SEQ ID NO: 37.

In one embodiment, the single functional human V gene segment is aV_(H)1-2 gene segment. In one embodiment, the V_(H)1-2 gene segmentcomprises SEQ ID NO: 63. In one embodiment, the V_(H)1-2 gene segment isderived from SEQ ID NO: 63. In one embodiment, the V_(H)1-2 gene segmentis at least 80%, at least 85%, at least 90%, at least 95%, or at least98% identical to SEQ ID NO: 63.

In one embodiment, the single functional human V gene segment is encodedby a nucleotide sequence comprising SEQ ID NO: 63.

In one embodiment, the single functional human V segment is operablylinked to one or more D segments and one or more J segments, or one ormore J segments. In one embodiment, the V segment and one or more Dand/or J segments are operably linked to an immunoglobulin heavy chainconstant region sequence. In one embodiment the immunoglobulin heavychain constant region sequence is selected from a C_(H)1, a hinge, aC_(H)2, a C_(H)3 sequence, and a combination thereof. In one embodiment,the C_(H)1, hinge, C_(H)2, C_(H)3, or combination thereof are eachnon-human endogenous constant sequences. In one embodiment, at least oneof the C_(H)1, hinge, C_(H)2, C_(H)3, or combination thereof is a humansequence. In a specific embodiment, the C_(H)1 and/or hinge are humansequences.

In one aspect, a modified endogenous non-human immunoglobulin heavychain locus is provided, comprising a replacement of all functional Vsegments with a single human V segment, wherein the non-humanimmunoglobulin heavy chain locus is incapable of rearrangement to form aheavy chain variable gene that is derived from a V segment other thanthe single human V segment.

In one embodiment, the single human V segment is V_(H)1-69. In oneembodiment, the single human V segment is V_(H)1-2.

In one embodiment, the locus comprises at least one human or non-humanD_(H) segment, and one human or non-human J_(H) segment. In a specificembodiment, the locus comprises a human D_(H) segment and a human J_(H)segment. In a specific embodiment, the locus comprises a human J_(H)segment. In another specific embodiment, the locus comprises a humanV_(H)1-69, all functional human D_(H) segments, and all functional humanJ_(H) segments. In one embodiment, the human V, D, and J segments (or Vand J segments) are operably linked to a mouse constant region gene atan endogenous mouse heavy chain locus. In a specific embodiment, themouse heavy chain locus comprises a wild-type repertoire of mouseimmunoglobulin constant region sequences.

In one aspect, a genetically modified non-human animal is provided,wherein the only functional immunoglobulin heavy chain V gene segment ofthe non-human animal is selected from a human V_(H)1-2, V_(H)1-3,V_(H)1-8, V_(H)1-18, V_(H)1-24, V_(H)1-45, V_(H)1-46, V_(H)1-58,V_(H)1-69, V_(H)2-5, V_(H)2-26, V_(H)2-70, V_(H)3-7, V_(H)3-9,V_(H)3-11, V_(H)3-13, V_(H)3-15, V_(H)3-16, V_(H)3-20, V_(H)3-21,V_(H)3-23, V_(H)3-30, V_(H)3-30-3, V_(H)3-30-5, V_(H)3-33, V_(H)3-35,V_(H)3-38, V_(H)3-43, V_(H)3-48, V_(H)3-49, V_(H)3-53, V_(H)3-64,V_(H)3-66, V_(H)3-72, V_(H)3-73, V_(H)3-74, V_(H)4-4, V_(H)4-28,V_(H)4-30-1, V_(H)4-30-2, V_(H)4-30-4, V_(H)4-31, V_(H)4-34, V_(H)4-39,V_(H)4-59, V_(H)4-61, V_(H)5-51, V_(H)6-1, V_(H)7-4-1, and a V_(H)7-81segment. In one embodiment, the heavy chain V gene segment is a humanV_(H)1-69 gene segment. In one embodiment, the heavy chain V genesegment is a human V_(H)1-2 gene segment.

In one aspect, a genetically modified non-human animal is provided,wherein the non-human animal comprises a single functional human V_(H)segment, and wherein the non-human animal is substantially incapable offorming a rearranged immunoglobulin heavy chain variable domain genethat lacks the single functional human V_(H) segment.

In one aspect, a genetically modified non-human animal is provided,wherein the only immunoglobulin heavy chain variable region expressed inthe non-human animal is derived from one of a human segment selectedfrom a human V_(H)1-2, V_(H)1-3, V_(H)1-8, V_(H)1-18, V_(H)1-24,V_(H)1-45, V_(H)1-46, V_(H)1-58, V_(H)1-69, V_(H)2-5, V_(H)2-26,V_(H)2-70, V_(H)3-7, V_(H)3-9, V_(H)3-11, V_(H)3-13, V_(H)3-15,V_(H)3-16, V_(H)3-20, V_(H)3-21, V_(H)3-23, V_(H)3-30, V_(H)3-30-3,V_(H)3-30-5, V_(H)3-33, V_(H)3-35, V_(H)3-38, V_(H)3-43, V_(H)3-48,V_(H)3-49, V_(H)3-53, V_(H)3-64, V_(H)3-66, V_(H)3-72, V_(H)3-73,V_(H)3-74, V_(H)4-4, V_(H)4-28, V_(H)4-30-1, V_(H)4-30-2, V_(H)4-30-4,V_(H)4-31, V_(H)4-34, V_(H)4-39, V_(H)4-59, V_(H)4-61, V_(H)5-51,V_(H)6-1, V_(H)7-4-1, and a V_(H)7-81 gene segment. In one embodiment,the human segment is a V_(H)1-69 segment. In one embodiment, the humansegment is a V_(H)1-2 segment. In one embodiment, the onlyimmunoglobulin heavy chain variable region expressed by the mouse isderived from a single V segment family member, and in one embodiment theonly immunoglobulin heavy chain variable region is derived from apolymorphic variant of the single V segment family member.

In one aspect, a non-human animal comprising a restricted immunoglobulinheavy chain V gene segment repertoire is provided, wherein the non-humananimal further comprises one or more human immunoglobulin κ light chainvariable segments (Vκ). In one embodiment, the one or more Vκ segmentsare operably linked to one or more human J segments. In a specificembodiment, the J segments are human Jκ segments. In another specificembodiment, the non-human animal does not express an immunoglobulin λlight chain. In another specific embodiment, the non-human animal doesnot comprise a functional human or functional endogenous immunoglobulinλ light chain variable locus.

In one embodiment, the non-human animal is a mouse.

In one embodiment, the non-human animal comprises a replacement at theendogenous non-human immunoglobulin Vκ locus of all or substantially allfunctional endogenous Vκ segments with one or more functional human Vκsegments. In a further specific embodiment, the replacement is with allor substantially all functional human immunoglobulin Vκ segments.

In one embodiment, the non-human animal comprises a replacement at theendogenous non-human immunoglobulin Jκ locus of all or substantially allfunctional endogenous non-human immunoglobulin Jκ segments with one ormore functional human immunoglobulin Jκ segments. In a further specificembodiment, the replacement is with all or substantially all functionalhuman immunoglobulin Jκ segments.

In a specific embodiment, the non-human animal comprises animmunoglobulin heavy chain variable region locus that comprises arepertoire of V segments consisting essentially of a single V segmentand/or polymorphic variants thereof. In one embodiment, the singleimmunoglobulin heavy chain V segment is a human V_(H)1-69 segment, andthe non-human animal further comprises a replacement of all functionalnon-human D_(H) segments with all functional human D_(H) segments, andfurther comprises a replacement of all functional non-human J_(H)segments with all functional human J_(H) segments, and wherein theimmunoglobulin heavy chain variable region locus is operably linked to ahuman or non-human constant region gene sequence. In a specificembodiment, the constant region gene sequence is an endogenous non-humanconstant region gene sequence. In a specific embodiment, the non-humananimal rearranges segments at the non-human immunoglobulin heavy chainlocus to form a gene encoding heavy chain variable region comprising ahuman V_(H)1-69 sequence, a human D_(H) sequence, a human J_(H)sequence, and a mouse constant region sequence.

In a specific embodiment, the non-human animal comprises animmunoglobulin heavy chain variable region locus that comprises arepertoire of V segments consisting essentially of a single V segmentand/or polymorphic variants thereof. In one embodiment, the singleimmunoglobulin heavy chain V segment is a human V_(H)1-2 segment, andthe non-human animal further comprises a replacement of all functionalnon-human D_(H) segments with all functional human D_(H) segments, andfurther comprises a replacement of all functional non-human J_(H)segments with all functional human J_(H) segments, and wherein theimmunoglobulin heavy chain variable region locus is operably linked to ahuman or non-human constant region gene sequence. In a specificembodiment, the constant region gene sequence is an endogenous non-humanconstant region gene sequence. In a specific embodiment, the non-humananimal rearranges segments at the non-human immunoglobulin heavy chainlocus to form a gene encoding heavy chain variable region comprising ahuman V_(H)1-2 sequence, a human D_(H) sequence, a human J_(H) sequence,and a mouse constant region sequence.

In one embodiment, a B cell is provided that comprises the rearrangedgene. In a specific embodiment, the B cell is from a mouse as describedthat has been immunized with an antigen of interest, and the B cellencodes an antibody that specifically binds the antigen of interest. Inone embodiment, the antigen of interest is a pathogen. In a specificembodiment, the pathogen is selected from an influenza virus, ahepatitis virus (e.g., hepatitis B or hepatitis C virus), and a humanimmunodeficiency virus. In a specific embodiment, the B cell encodes asomatically mutated, high affinity (e.g., about 10⁻⁹ K_(D) or lower)antibody comprising a human light chain variable region (e.g., a human κlight chain variable region) that specifically binds the antigen ofinterest.

In one aspect, a non-human animal comprising a restricted immunoglobulinheavy chain V segment repertoire is provided, wherein the non-humananimal comprises one or more human λ light chain variable (Vλ) segments.In one embodiment, the one or more human Vλ segments are operably linkedto one or more human J segments. In a specific embodiment, the Jsegments are human Jλ segments. In another specific embodiment, thenon-human animal does not express a κ light chain. In another specificembodiment, the non-human animal does not comprise a functional human ornon-human κ light chain variable locus.

In one embodiment, the non-human animal comprises a replacement of allor substantially all functional non-human immunoglobulin Vλ segmentswith one or more functional human immunoglobulin Vλ segments. In afurther specific embodiment, the replacement is with all orsubstantially all functional human immunoglobulin Vλ segments.

In one embodiment, the non-human animal comprises a replacement of allor substantially all functional non-human immunoglobulin Jλ segmentswith one or more functional human immunoglobulin Jλ segments. In afurther specific embodiment, the replacement is with all orsubstantially all functional human immunoglobulin Jλ segments.

In a specific embodiment, the non-human animal comprises animmunoglobulin heavy chain variable (V_(H)) region locus that comprisesonly a single V_(H) segment, wherein the single V_(H) segment is a humanV_(H)1-69 segment or a human V_(H)1-2 segment, and further comprises areplacement of all functional non-human D_(H) segments with allfunctional human D_(H) segments, and further comprises a replacement ofall functional non-human J_(H) segments with all functional human J_(H)segments, and wherein the V_(H) region locus is operably linked to ahuman or non-human constant region gene sequence. In a specificembodiment, the constant region gene sequence is a non-human constantregion gene sequence, e.g., an endogenous non-human constant genesequence. In a specific embodiment, the non-human animal rearrangessegments at the non-human immunoglobulin heavy chain locus to form agene encoding an immunoglobulin heavy chain variable region comprising ahuman V_(H)1-69 sequence (or a human V_(H)1-2 sequence), a human D_(H)sequence, a human J_(H) sequence, and an endogenous non-human constantregion sequence.

In one embodiment, a B cell is provided that comprises the rearrangedgene. In a specific embodiment, the B cell is from a non-human animal asdescribed that has been immunized with an antigen of interest, and the Bcell encodes an antibody that specifically binds the antigen ofinterest. In one embodiment, the antigen is a human protein selectedfrom a ligand, a cell surface receptor and an intracellular protein. Inone embodiment, the antigen of interest is a pathogen. In a specificembodiment, the pathogen is selected from an influenza virus, ahepatitis virus (e.g., hepatitis B or hepatitis C virus), and a humanimmunodeficiency virus. In a specific embodiment, the B cell encodes asomatically mutated, high affinity (e.g., about 10⁻⁹ K_(D) or lower)antibody comprising a human light chain variable region (e.g., a human λlight chain variable region) that specifically binds the antigen ofinterest.

In one aspect, a non-human animal comprising a restricted immunoglobulinheavy chain V segment repertoire is provided, wherein the non-humananimal comprises a human V_(H)1-69 segment (or a human V_(H)1-2 segment)on a transgene, wherein the human V_(H)1-69 segment is operably linkedon the transgene to a human or non-human D_(H) segment, and/or a humanor non-human J segment, and the transgene further comprises a human ornon-human constant region gene, or a chimeric human/non-human constantregion (e.g., a C_(H)1, hinge, C_(H)2, C_(H)3 or combination thereofwherein at least one sequence is non-human, e.g., selected from hinge,C_(H)2, and C_(H)3 and/or hinge). In one embodiment, the non-humananimal is a mouse or rat and the non-human D, J, and/or constant regiongene is a mouse or rat gene or chimeric human/mouse or rat.

In one embodiment, the non-human animal comprises a transgene thatcomprises an immunoglobulin light chain variable region locus thatcomprises one or more human immunoglobulin Vλ segments and Jλ segments,or one or more human immunoglobulin Vκ segments and Jκ segments, and ahuman immunoglobulin κ or λ light chain constant region gene, such thatthe transgene rearranges in the non-human animal to form a rearrangedimmunoglobulin κ or λ light chain gene.

In a specific embodiment, the non-human animal comprises a transgenehaving an immunoglobulin heavy chain variable locus that comprises asingle V segment that is a human V_(H)1-69 segment (or a human V_(H)1-2segment), one or more human D segments, one or more human J segments,and a human constant gene operably linked to the heavy chain variablelocus, such that the mouse expresses from the transgene a fully humanantibody derived from the V_(H)1-69 segment (or the V_(H)1-2 segment).In one embodiment, the non-human animal does not comprise a functionalendogenous immunoglobulin heavy chain variable region locus. In aspecific embodiment, the non-human animal comprises a nonfunctionalendogenous immunoglobulin heavy chain variable region locus thatcomprises a deletion of an endogenous non-human D_(H) and/or endogenousnon-human J_(H) segment, such that the non-human animal is incapable ofrearranging the endogenous immunoglobulin heavy chain variable regionlocus to form a rearranged non-human antibody gene. In a specificembodiment, the non-human animal comprises a deletion of a switchsequence operably linked to an endogenous mouse heavy chain constantregion. In a specific embodiment, the switch sequence is a non-human(e.g., mouse) μ switch sequence. In another embodiment, the non-humananimal further comprises a lack of a functional endogenous light chainvariable locus selected from an immunoglobulin κ locus and animmunoglobulin λ locus. In a specific embodiment, the non-human animalcomprises a deletion of a Jκ and/or a Jλ sequence, such that thenon-human animal is incapable of rearranging an endogenous non-humanimmunoglobulin κ light chain and/or an endogenous non-humanimmunoglobulin λ light chain variable region to form a rearrangedendogenous non-human immunoglobulin κ light chain and/or a rearrangedendogenous non-human immunoglobulin λ light chain gene.

In one embodiment, the non-human animal comprises a deletion of anendogenous non-human immunoglobulin κ light chain sequence that resultsin a functional knockout of the endogenous non-human immunoglobulin κlight chain. In one embodiment, the non-human animal comprises adeletion of an endogenous non-human immunoglobulin λ light chainsequence that results in a functional knockout of the endogenousnon-human immunoglobulin λ light chain.

In one aspect, a rodent is provided that comprises an immunoglobulinheavy chain variable repertoire derived from no more than one humanV_(H) segment or one or more polymorphs thereof, from a D segmentselected from a repertoire of one or more D segments, and from a Jsegment selected from a repertoire of one or more J segments; whereinthe rodent comprises an ectopic ADAM6 sequence or ortholog or homolog orfragment thereof that is functional in a male rodent.

In one embodiment, the human V_(H) segment is present in 1, 2, 3, 4, 5,6, 7, 8, 9, or 10 or more polymorphic variants, wherein each polymorphicvariant is operably linked to a D and/or J segment such that eachpolymorphic variant is capable of rearranging and forming a rearrangedheavy chain variable domain with any of the one or more D segments andany of the one or more J segments. In one embodiment, the rodent is amouse or a rat. In one embodiment, the repertoire of D segmentscomprises two or more D segments. In one embodiment, the repertoire of Jsegments comprises two or more J segments. In one embodiment, the Dand/or J segments are human segments. In one embodiment, the ectopicADAM6 sequence is an ADAM6 sequence of a wild-type rodent of the samespecies. In one embodiment, the rodent is a mouse or a rat. In oneembodiment, the ectopic ADAM6 sequence or ortholog or homolog orfragment thereof that is functional in the male rodent is on the samechromosome as the modified immunoglobulin heavy chain variablerepertoire; in one embodiment, it is on a different chromosome.

In one aspect, a nucleotide construct is provided that comprises asequence encoding a single human immunoglobulin heavy chain V_(H)segment and/or polymorphic variants thereof and one or more D_(H) andone or more J sequences, wherein the construct comprises at least onehomology arm homologous to a non-human immunoglobulin heavy chainvariable locus, or a recombinase recognition site (e.g., a lox site). Inone embodiment, the V segment is a V_(H)1-69 segment or a V_(H)1-2segment.

In one aspect, a nucleotide construct is provided, comprising anucleotide sequence encoding a single human immunoglobulin heavy chain Vsegment, wherein the single V_(H) segment is a V_(H)1-69 (or V_(H)1-2)segment. In one embodiment, the construct comprises a site-specificrecombinase recognition site. In one embodiment, the construct comprisesa first mouse homology arm upstream of the V_(H)1-69 (or V_(H)1-2)segment and a second mouse homology arm downstream of the V_(H)1-69 (orV_(H)1-2) segment, and wherein the first mouse homology arm ishomologous to a region of a mouse chromosome immediately upstream of amouse immunoglobulin heavy chain variable region but not including afunctional mouse immunoglobulin heavy chain variable segment. In oneembodiment, the construct comprises SEQ ID NO: 6. In one embodiment, theconstruct comprises SEQ ID NO: 74. In one embodiment, the constructcomprises SEQ ID NO: 75. In one embodiment, the construct comprises SEQID NO: 76.

In one aspect, the restricted single V_(H) segment is in a non-humananimal, or the restricted V_(H) segment is at a non-human immunoglobulinheavy chain locus (e.g., in situ or in a transgene), and the non-humananimal or non-human immunoglobulin heavy chain locus is selected from amouse, rat, rabbit, pig, bovine (e.g., cow, bull, buffalo), deer, sheep,goat, chicken, cat, dog, ferret, primate (e.g., marmoset, rhesus monkey)locus or animal. In a specific embodiment, the non-human animal or locusis a mouse or a rat locus.

In one aspect, a targeting vector is provided, comprising (a) anucleotide sequence that is identical or substantially identical to ahuman variable region gene segment nucleotide sequence; and, (b) anucleotide sequence encoding a mouse ADAM6 or ortholog or homolog orfragment thereof that is functional in a mouse.

In one embodiment, the targeting vector further comprises a promoteroperably linked to the sequence encoding the mouse ADAM6. In a specificembodiment, the promoter is a mouse ADAM6 promoter.

In one aspect, a nucleotide construct for modifying a mouseimmunoglobulin heavy chain variable locus is provided, wherein theconstruct comprises at least one site-specific recombinase recognitionsite and a sequence encoding an ADAM6 protein or ortholog or homolog orfragment thereof that is functional in a mouse.

In one aspect, a nucleic acid construct is provided, comprising anupstream homology arm and a downstream homology arm, wherein theupstream homology arm comprises a sequence that is identical orsubstantially identical to a human immunoglobulin heavy chain variableregion sequence, the downstream homology arm comprises a sequence thatis identical or substantially identical to a human or mouseimmunoglobulin variable region sequence, and disposed between theupstream and downstream homology arms is a sequence that comprises anucleotide sequence encoding a mouse ADAM6 protein. In a specificembodiment, the sequence encoding the mouse ADAM6 gene is operablylinked with a mouse promoter with which the mouse ADAM6 is linked in awild type mouse.

In one aspect, a cell isolated from a genetically modified mouse asdescribed herein is provided. In one embodiment, the cell is alymphocyte. In one embodiment, the lymphocyte is a B cell. In a specificembodiment, the B cell comprises an ectopic ADAM6 sequence or orthologor homolog or sequence encoding a functional fragment thereof, whereinthe B cell expresses a heavy chain variable domain derived from a humanV_(H) gene segment.

In one aspect, a cell or tissue is provided, wherein the cell or tissueis derived from a non-human animal as described herein, and comprises arestricted V_(H) segment repertoire. In one embodiment, the V_(H)segment repertoire is restricted to a single V_(H) segment family memberand/or polymorphic variants thereof. In a specific embodiment, thesingle V_(H) segment is a human V_(H)1-69 segment or a human V_(H)1-2segment. In one embodiment, the cell or tissue is derived from spleen,lymph node or bone marrow of the non-human animal.

In one embodiment, the cell is an ES cell. In one embodiment, the cellis a B cell. In one embodiment, the cell is a germ cell.

In one embodiment, the tissue is selected from connective, muscle,nervous and epithelial tissue. In a specific embodiment, the tissue isreproductive tissue.

In one embodiment, the cell and/or tissue derived from a mouse asdescribed herein is isolated for use in one or more ex vivo assays. Invarious embodiments, the one or more ex vivo assays include measurementsof physical, thermal, electrical, mechanical or optical properties, asurgical procedure, measurements of interactions of different tissuetypes, the development of imaging techniques, or a combination thereof.

In one embodiment, the non-human animal is a mouse.

In one aspect, a non-human embryo is provided comprising a restrictedheavy chain V_(H) segments as described herein. In one embodiment, theembryo comprises an ES donor cell that comprises the restricted V_(H)segment, and host embryo cells.

In one embodiment, the non-human animal is a mouse.

In one aspect, a non-human cell comprising a chromosome or fragmentthereof of a non-human animal as described herein. In one embodiment,the non-human cell comprises a nucleus of a non-human animal asdescribed herein. In one embodiment, the non-human cell comprises thechromosome or fragment thereof as the result of a nuclear transfer.

In one aspect, a nucleus derived from a non-human animal as describedherein is provided. In one embodiment, the nucleus is from a diploidcell that is not a B cell.

In one aspect, a pluripotent, induced pluripotent, or totipotent cellderived from a non-human animal as described herein is provided. In aspecific embodiment, the cell is a mouse embryonic stem (ES) cell.

In one aspect, a non-human induced pluripotent cell comprising arestricted V_(H) segment repertoire is provided. In one embodiment, theinduced pluripotent cell is derived from a non-human animal as describedherein.

In one aspect a hybridoma is provided, comprising a sequence of alymphocyte of a mouse as described herein. In one embodiment, thelymphocyte is a B cell.

In one aspect, a hybridoma or quadroma is provided, derived from a cellof a non-human animal as described herein. In one embodiment, thenon-human animal is a mouse or rat.

In one aspect, mouse cells and mouse embryos are provided, including butnot limited to ES cells, pluripotent cells, and induced pluripotentcells, that comprise genetic modifications as described herein. Cellsthat are XX and cells that are XY are provided. Cells that comprise anucleus containing a modification as described herein are also provided,e.g., a modification introduced into a cell by pronuclear injection.Cells, embryos, and mice that comprise a virally introduced ADAM6 geneare also provided, e.g., cells, embryos, and mice comprising atransduction construct comprising an ADAM6 gene that is functional inthe mouse.

In one aspect, a genetically modified mouse cell is provided, whereinthe cell is incapable of expressing a heavy chain comprising rearrangedendogenous immunoglobulin heavy chain gene segments, and the cellcomprises a functional ADAM6 gene that encodes a mouse ADAM6 protein orfunctional fragment thereof. In one embodiment, the cell furthercomprises an insertion of human immunoglobulin gene segments. In aspecific embodiment, the human immunoglobulin gene segments are heavychain gene segments that are operably linked to mouse heavy chainconstant regions such that upon rearrangement encode a functional heavychain of an antibody that comprises a human variable region.

In one aspect, a genetically modified mouse cell is provided; whereinthe cell lacks a functional endogenous mouse ADAM6 locus, and the cellcomprises an ectopic nucleotide sequence that encodes a mouse ADAM6protein or functional fragment thereof. In one embodiment, the cellfurther comprises a modification of an endogenous immunoglobulin heavychain variable gene sequence. In a specific embodiment, the modificationof the endogenous immunoglobulin heavy chain variable gene sequencecomprises a deletion selected from a deletion of a mouse V_(H) genesegment, a deletion of a mouse D_(H) gene segment, a deletion of a mouseJ_(H) gene segment, and a combination thereof. In a specific embodiment,the mouse comprises a replacement of one or more mouse immunoglobulinV_(H), D_(H), and/or J_(H) sequences with a human immunoglobulinsequence. In a specific embodiment, the human immunoglobulin sequence isselected from a human V_(H), a human V_(L), a human D_(H), a humanJ_(H), a human J_(L), and a combination thereof.

In one embodiment, the cell is a totipotent cell, a pluripotent cell, oran induced pluripotent cell. In a specific embodiment, the cell is amouse ES cell.

In one aspect, a mouse B cell is provided, wherein the mouse B cellcomprises a rearranged immunoglobulin heavy chain gene, wherein the Bcell comprises on a chromosome of the B cell a nucleic acid sequenceencoding an ADAM6 protein or ortholog or homolog or fragment thereofthat is functional in a male mouse. In one embodiment, the mouse B cellcomprises two alleles of the nucleic acid sequence.

In one embodiment, the nucleic acid sequence is on a nucleic acidmolecule (e.g., a B cell chromosome) that is contiguous with therearranged mouse immunoglobulin heavy chain locus.

In one embodiment, the nucleic acid sequence is on a nucleic acidmolecule (e.g., a B cell chromosome) that is distinct from the nucleicacid molecule that comprises the rearranged mouse immunoglobulin heavychain locus.

In one embodiment, the mouse B cell comprises a rearranged non-mouseimmunoglobulin variable gene sequence operably linked to a mouse orhuman immunoglobulin constant region gene, wherein the B cell comprisesa nucleic acid sequence that encodes an ADAM6 protein or ortholog orhomolog or fragment thereof that is functional in a male mouse.

In one embodiment, the nucleic acid sequence is on a nucleic acidmolecule (e.g., a B cell chromosome) that is located at or within thenearest gene locus with respect to the rearranged non-humanimmunoglobulin variable gene sequence.

In one embodiment, the nucleic acid sequence is on a nucleic acidmolecule (e.g., a B cell chromosome) that is contiguous with therearranged non-human immunoglobulin variable region sequence.

In one aspect, a somatic mouse cell is provided, comprising a chromosomethat comprises a modified immunoglobulin heavy chain locus, and anucleic acid sequence encoding a mouse ADAM6 or ortholog or homolog orfragment thereof that is functional in a male mouse. In one embodiment,the nucleic acid sequence is on the same chromosome as the modifiedimmunoglobulin heavy chain locus. In one embodiment, the nucleic acid ison a different chromosome than the modified immunoglobulin heavy chainlocus. In one embodiment, the somatic cell comprises a single copy ofthe nucleic acid sequence. In one embodiment, the somatic cell comprisesat least two copies of the nucleic acid sequence. In a specificembodiment, the somatic cell is a B cell. In a specific embodiment, thecell is a germ cell. In a specific embodiment, the cell is a stem cell.

In one aspect, a mouse germ cell is provided, comprising a nucleic acidsequence encoding a mouse ADAM6 (or homolog or ortholog or functionalfragment thereof) on a chromosome of the germ cell, wherein the nucleicacid sequence encoding the mouse ADAM6 (or homolog or ortholog orfunctional fragment thereof) is at a position in the chromosome that isdifferent from a position in a chromosome of a wild-type mouse germcell. In one embodiment, the nucleic acid sequence is at a mouseimmunoglobulin locus. In one embodiment, the nucleic acid sequence is onthe same chromosome of the germ cell as a mouse immunoglobulin locus. Inone embodiment, the nucleic acid sequence is on a different chromosomeof the germ cell than the mouse immunoglobulin locus. In one embodiment,the mouse immunoglobulin locus comprises a replacement of at least onemouse immunoglobulin sequence with at least one non-mouse immunoglobulinsequence. In a specific embodiment, the at least one non-mouseimmunoglobulin sequence is a human immunoglobulin sequence. In oneembodiment, the human immunoglobulin sequence is an immunoglobulin heavychain sequence.

In one aspect, an antibody variable domain sequence made in a non-humananimal as described herein is provided.

In one aspect, a human therapeutic is provided, comprising an antibodyvariable domain comprising a sequence derived from a non-human animal asdescribed herein.

In one aspect, a method of obtaining an antibody variable regionsequence from a non-human animal is provided, wherein the antibodyvariable region sequence is derived from a human V_(H)1-69 segment or aV_(H)1-2 segment, wherein the method comprises (a) immunizing anon-human animal with an antigen of interest, wherein the non-humananimal comprises a replacement at the endogenous immunoglobulin heavychain locus of all or substantially all non-human variable segments witha single human variable segment, wherein the single human variablesegment is a V_(H)1-69 segment or a V_(H)1-2 segment, and wherein thenon-human animal is substantially incapable of forming a immunoglobulinheavy chain variable region sequence that is not derived from a humanV_(H)1-69 segment or a V_(H)1-2 segment; (b) allowing the non-humananimal to mount an immune response with respect to the antigen ofinterest; and, (c) identifying or isolating an immunoglobulin heavychain variable region sequence of the non-human animal, wherein theantibody binds the antigen of interest.

In one embodiment, the single human variable segment is a V_(H)1-69segment.

In one embodiment, the antibody variable region sequence is derived fromSEQ ID NO: 37. In one embodiment, the antibody variable region sequenceis at least 75%, at least 80%, at least 85%, at least 90%, at least 95%,or at least 98% identical to SEQ ID NO: 37. In one embodiment, theantibody variable region sequence comprises SEQ ID NO: 37.

In one embodiment the single human variable segment is a V_(H)1-2segment.

In one embodiment, the antibody variable region sequence is derived fromSEQ ID NO: 63. In one embodiment, the antibody variable region sequenceis at least 75%, at least 80%, at least 85%, at least 90%, at least 95%,or at least 98% identical to SEQ ID NO: 63. In one embodiment, theantibody variable region sequence comprises SEQ ID NO: 63.

In one aspect, a method for generating a repertoire of human antibodyvariable regions in a non-human animal is provided, wherein the humanheavy chain variable regions of the repertoire are derived from the sameV_(H) gene family member and one of a plurality of D_(H) segments andone of a plurality of J_(H) segments, wherein the repertoire ischaracterized by having heavy chain immunoglobulin FR1 (framework 1),CDR1, FR2, CDR2, and FR3 sequences from a single V_(H) gene familymember. In one embodiment, the repertoire is further characterized byhaving a plurality of different CDR3+FR4 sequences.

In one embodiment, the single V_(H) gene family is selected from V_(H)family 1, 2, 3, 4, 5, 6, and 7. In a specific embodiment, the singleV_(H) gene family is V_(H) family 1. In one embodiment, the single V_(H)gene family member is selected from V_(H)1-2, V_(H)1-69, V_(H)2-26,V_(H)2-70, and V_(H)3-23. In a specific embodiment, the single V_(H)gene family member is V_(H)1-69.

In one embodiment, the repertoire comprises heavy chain FR1, CDR1, FR2,CDR2 and FR3 sequences derived from a V_(H)1-69 segment. In a specificembodiment, the repertoire comprises heavy chain FR1, CDR1, FR2, CDR2and FR3 sequences derived from SEQ ID NO: 38. In a specific embodiment,the repertoire comprises heavy chain FR1, CDR1, FR2, CDR2 and FR3sequences of SEQ ID NO: 38.

In one embodiment, the repertoire comprises heavy chain FR1, CDR1, FR2,CDR2 and FR3 sequences derived from a V_(H)1-2 segment. In a specificembodiment, the repertoire comprises heavy chain FR1, CDR1, FR2, CDR2and FR3 sequences derived from SEQ ID NO: 64. In a specific embodiment,the repertoire comprises heavy chain FR1, CDR1, FR2, CDR2 and FR3sequences of SEQ ID NO: 64.

In one aspect, a method for generating a plurality of different CDR3 andFR4 sequences in a non-human animal is provided, comprising exposing anon-human animal that comprises an immunoglobulin heavy chain variablegene locus with a V_(H) segment repertoire restricted to a single V_(H)segment family member to an antigen of interest, allowing the non-humananimal to develop an immune response to the antigen, wherein the immuneresponse generates a B cell repertoire whose heavy chain variabledomains are each derived from the single V_(H) segment family member andthat comprise a plurality of different CDR3 and FR4 sequences.

In one embodiment, the singe V_(H) segment family member is human. Inone embodiment, the non-human animal is selected from a mouse, a rat,and a rabbit. In one embodiment, the antigen of interest is selectedfrom a ligand, a receptor, an intracellular protein and a secretedprotein. In one embodiment, the antigen of interest is a human pathogen.

In one aspect, a nucleotide sequence encoding an immunoglobulin variableregion made in a non-human animal as described herein is provided.

In one aspect, an immunoglobulin heavy chain or immunoglobulin lightchain variable region amino acid sequence of an antibody made in anon-human animal as described herein is provided.

In one aspect, an immunoglobulin heavy chain or immunoglobulin lightchain variable region nucleotide sequence encoding a variable region ofan antibody made in a non-human as described herein is provided.

In one aspect, an antibody or antigen-binding fragment thereof (e.g.,Fab, F(ab)₂, scFv) made in a non-human animal as described herein isprovided.

In one aspect, a method for making a genetically modified non-humananimal is provided, comprising replacing one or more immunoglobulinheavy chain gene segments upstream (with respect to transcription of theimmunoglobulin heavy chain gene segments) of an endogenous ADAM6 locusof the non-human animal with one or more human immunoglobulin heavychain gene segments, and replacing one or more immunoglobulin genesegments downstream (with respect to transcription of the immunoglobulinheavy chain gene segments) of the ADAM6 locus of the non-human animalwith one or more human immunoglobulin heavy chain or light chain genesegments. In one embodiment, the one or more human immunoglobulin genesegments replacing one or more endogenous immunoglobulin gene segmentsupstream of an endogenous ADAM6 locus of the non-human animal include Vgene segments. In one embodiment, the human immunoglobulin gene segmentsreplacing one or more endogenous immunoglobulin gene segments upstreamof an endogenous ADAM6 locus of the non-human animal include V and Dgene segments. In one embodiment, the one or more human immunoglobulingene segments replacing one or more endogenous immunoglobulin genesegments downstream of an endogenous ADAM6 locus of the non-human animalinclude J gene segments. In one embodiment, the one or more humanimmunoglobulin gene segments replacing one or more endogenousimmunoglobulin gene segments downstream of an endogenous ADAM6 locus ofthe non-human animal include D and J gene segments. In one embodiment,the one or more human immunoglobulin gene segments replacing one or moreendogenous immunoglobulin gene segments downstream of an endogenousADAM6 locus of the non-human animal include V, D and J gene segments. Ina specific embodiment, the one or more gene segments replacing one ormore endogenous immunoglobulin gene segments downstream of an endogenousADAM6 locus of the non-human animal includes a single V gene segment,one or more D gene segments and one or more J gene segments.

In one embodiment, the one or more immunoglobulin heavy chain genesegments upstream and/or downstream of the ADAM6 gene are replaced in apluripotent, induced pluripotent, or totipotent cell to form agenetically modified progenitor cell; the genetically modifiedprogenitor cell is introduced into a host; and, the host comprising thegenetically modified progenitor cell is gestated to form a non-humananimal comprising a genome derived from the genetically modifiedprogenitor cell. In one embodiment, the host is an embryo. In a specificembodiment, the host is selected from a mouse pre-morula (e.g., 8- or4-cell stage), a tetraploid embryo, an aggregate of embryonic cells, ora blastocyst.

In one aspect, a non-human animal is provided, wherein the non-humananimal has a B cell repertoire that expresses immunoglobulin heavy chainvariable domains derived from a single V segment family member. In oneembodiment, at least 10%, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90, or atleast 95% of the B cell repertoire of the non-human animalimmunoglobulin heavy chain variable domain expressed in the B cellrepertoire is derived from the same V segment family member. In aspecific embodiment, the percentage is at least 90%. In one embodiment,the B cell repertoire consists essentially of peripheral (blood) Bcells. In one embodiment, the B cell repertoire consists essentially ofsplenic B cells. In one embodiment, the B cell repertoire consistsessentially of bone marrow B cells. In one embodiment, the B cellrepertoire consists essentially of peripheral B cells, splenic B cells,and bone marrow B cells.

In one aspect, a genetically modified non-human animal is provided,wherein more than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or more than90% of the B cells of the non-human animal that express a heavy chainimmunoglobulin variable domain express a heavy chain immunoglobulinvariable domain derived from a single V_(H) gene segment family member.In one embodiment, at least 75% of the B cells of the non-human animalthat express an immunoglobulin heavy chain variable domain express animmunoglobulin heavy chain variable domain derived from the single V_(H)gene segment family member. In a specific embodiment, the percentage isat least 90%. In one embodiment, all of the B cells that express a heavychain domain that is derived from the single V_(H) gene family member.

In one aspect, a genetically modified mouse is provided that makes anantigen-specific B cell population in response to immunization with anantigen of interest, wherein at least 10%, 20%, 30%, 40%, 50%, 60%, 70%,80%, or more than 90%, of said antigen-specific B cell populationexpresses immunoglobulin heavy chains that are all derived from the sameV_(H) gene segment. In one embodiment, at least 75% of theantigen-specific B cell population expresses immunoglobulin heavy chainsderived from the same V_(H) gene segment. In one embodiment, all of theantigen-specific B cells express a heavy chain that is derived from thesame V_(H) gene segment.

In one aspect, a non-human animal comprising a restricted V_(H) genesegment repertoire is provided, wherein the restriction is to a humanV_(H)1-69 gene segment or a V_(H)1-69 gene segment that is at leastabout 75.5%, 76.5%, 86.7%, 87.8%, 94.9%, 96.9%, 98%, or 99% identical toa V_(H)1-69*01 gene segment. In a specific embodiment, the restrictedrepertoire is selected from one or more of the V_(H)1-69 variants ofFIG. 7.

In one aspect, a non-human animal comprising a restricted V_(H) genesegment repertoire is provided, wherein the restriction is to a humanV_(H)1-2 gene segment or a V_(H)1-2 gene segment that is at least about94.9%, 95.9%, 96.9%, 98%, or 99% identical to a V_(H)1-2 gene segment.In a specific embodiment, the restricted repertoire is selected from oneor more of the V_(H)1-2 variants of FIG. 10.

In one embodiment, the non-human animal is a mouse.

In one aspect, a non-human animal comprising a restricted human V_(H)segment repertoire is provided, further comprising a humanizedimmunoglobulin light chain variable segment locus, wherein the ratio ofλ to κ light chains expressed in the mouse is about the same as in awild-type mouse.

In one aspect, a non-human animal is provided, comprising a restrictedimmunoglobulin heavy chain locus characterized by the presence of asingle V_(H) gene segment, one or more D_(H) gene segments, and one ormore J_(H) gene segments, wherein the single V_(H) gene segment is apolymorphic V_(H) gene segment.

In one embodiment, the polymorphic V_(H) gene segment is a human V_(H)gene segment that is associated with a high copy number in humanpopulations. In one embodiment, the human V_(H) gene segment is selectedfrom V_(H)1-2, V_(H)1-69, V_(H)2-26, V_(H)2-70, V_(H)3-23, or apolymorphic variant thereof. In a specific embodiment, the human V_(H)gene segment is a V_(H)1-69 gene segment. In another specificembodiment, the human V_(H) gene segment is a V_(H)1-2 gene segment.

In one embodiment, the single V_(H) gene segment is operably linked to ahuman, mouse, or chimeric human/mouse immunoglobulin constant regiongene. In a specific embodiment, the immunoglobulin constant region geneis a mouse constant region gene. In one embodiment, the immunoglobulinconstant gene comprises a human sequence selected from a human C_(H)1, ahuman hinge, a human C_(H)2, a human C_(H)3, and a combination thereof.In one embodiment, the mouse constant gene is at an endogenousimmunoglobulin heavy chain locus.

In one embodiment, the non-human animal further comprises a humanimmunoglobulin V_(L) gene segment operably linked to a J gene segmentand a light chain constant gene. In a specific embodiment, the V_(L)gene segment and/or the J gene segment are selected from a human κ genesegment and a human λ gene segment. In one embodiment, the V_(L) and/orJ gene segments are human κ gene segments.

In various embodiments, the non-human animal comprises a deletion of allor substantially all endogenous V_(H) gene segments.

In various embodiments, the non-human animal comprises an inactivatedendogenous heavy chain variable gene locus. In various embodiments, theinactivated endogenous heavy chain variable gene locus is not operablylinked to an endogenous heavy chain constant region gene.

In one aspect, a non-human animal is provided, wherein the non-humananimal is characterized by the expression of serum immunoglobulin,wherein greater than 80% of the serum immunoglobulin comprises a humanheavy chain variable domain and a cognate human light chain variabledomain, wherein the human heavy chain variable domain is derived from aV_(H) gene segment repertoire consisting essentially of a single humanV_(H) gene segment and/or polymorphic variants thereof.

In one embodiment, the single human V_(H) gene segment is a humanV_(H)1-69 gene segment and/or polymorphic variants thereof. In oneembodiment, the single human V_(H) gene segment is a human V_(H)1-2 genesegment and/or polymorphic variants thereof.

In one aspect, a non-human animal is provided, comprising, in itsgermline, a replacement at an endogenous immunoglobulin heavy chainlocus of all or substantially all endogenous V_(H) gene segments with asingle human V_(H) gene segment and/or polymorphic variants thereof.

In one embodiment, the non-human animal further comprises a replacementat an endogenous immunoglobulin light chain locus of all orsubstantially all endogenous V_(t) gene segments with one or more humanV_(L) gene segments. In a specific embodiment, the mouse furthercomprises one or more human J_(L) gene segments operably linked to thehuman V_(L) gene segments.

In one aspect, a non-human animal that expresses an antibody thatcomprises at least one human variable domain/non-human constant domainimmunoglobulin polypeptide is provided, wherein the non-human animalexpresses a non-human ADAM6 protein or ortholog or homolog thereof froman endogenous immunoglobulin heavy chain locus. In one embodiment, theendogenous immunoglobulin heavy chain locus is incapable of rearrangingto encode a functional heavy chain of an antibody.

In one aspect, a non-human animal that expresses an antibody thatcomprises at least one human variable domain/non-human constant domainimmunoglobulin polypeptide is provided, wherein the non-human animalexpresses a non-human ADAM6 protein or ortholog or homolog thereof froma locus other than an immunoglobulin locus.

In one embodiment, the ADAM6 protein or ortholog or homolog thereof isexpressed in a B cell of the non-human animal, wherein the B cellcomprises a rearranged immunoglobulin sequence that comprises a humanvariable sequence and a non-human constant sequence.

In one embodiment, the non-human constant sequence is a rodent sequence.In one embodiment, the rodent is selected from a mouse, a rat, and ahamster.

In one aspect, a method is provided for making an infertile malenon-human animal, comprising rendering an endogenous ADAM6 allele of adonor ES cell nonfunctional (or knocking out said allele), introducingthe donor ES cell into a host embryo, gestating the host embryo in asurrogate mother, and allowing the surrogate mother to give birth toprogeny derived in whole or in part from the donor ES cell. In oneembodiment, the method further comprises breeding progeny to obtain aninfertile male non-human animal.

In one aspect, a method is provided for making a non-human animal with agenetic modification of interest, wherein the non-human animal isinfertile, the method comprising the steps of (a) making a geneticmodification of interest in a genome; (b) modifying the genome toknockout an endogenous ADAM6 allele, or render an endogenous ADAM6allele nonfunctional; and, (c) employing the genome in making anon-human animal. In various embodiments, the genome is from an ES cellor used in a nuclear transfer experiment.

In one aspect, a non-human animal made using a targeting vector,nucleotide construct, or cell as described herein is provided.

In one aspect, a progeny of a mating of a non-human animal as describedherein with a second non-human animal that is a wild-type non-humananimal or genetically modified is provided.

In one aspect, a method for maintaining a non-human animal strain isprovided, wherein the non-human animal strain comprises a replacement ofa non-human immunoglobulin heavy chain sequence with one or moreheterologous immunoglobulin heavy chain sequences. In one embodiment,the one or more heterologous immunoglobulin heavy chain sequences arehuman immunoglobulin heavy chain sequences.

In one embodiment, the non-human animal strain comprises a deletion ofone or more non-human V_(H), D_(H), and/or J_(H) gene segments. In oneembodiment, the non-human animal further comprises a single human V_(H)gene segment, one or more human D_(H) gene segments, and/or one or morehuman J_(H) gene segments. In one embodiment, the non-human animalcomprises a single human V_(H) segment, at least 27 human D_(H) genesegments, and at least six J_(H) gene segments. In a specificembodiment, the non-human animal comprises a single human V_(H) segment,27 human D_(H) gene segments, and six human J_(H) gene segments, whereinsaid single human V_(H) gene segment, 27 human D_(H) gene segments, andsix human J_(H) gene segments are operably linked to a constant regiongene. In one embodiment, the constant region gene is a non-humanconstant region gene. In one embodiment, the constant region genecomprises a mouse or rat constant region gene sequence selected from aC_(H)1, a hinge, a C_(H)2, a C_(H)3, and/or a C_(H)4 or a combinationthereof. In various embodiments, the single human V_(H) gene segment isa human V_(H)1-69 or a human V_(H)1-2 gene segment.

In one embodiment, the method comprises generating a male non-humananimal heterozygous for the replacement of the non-human immunoglobulinheavy chain sequence, and breeding the heterozygous male non-humananimal with a wild-type female non-human animal or a female non-humananimal that is homozygous or heterozygous for the human heavy chainsequence. In one embodiment, the method comprises maintaining thenon-human animal strain by repeatedly breeding heterozygous males withfemales that are wild type or homozygous or heterozygous for the humanheavy chain sequence.

In one embodiment, the method comprises obtaining cells from male orfemale non-human animals homozygous or heterozygous for the human heavychain sequence, and employing those cells as donor cells or nucleitherefrom as donor nuclei, and using the cells or nuclei to makegenetically modified non-human animals using host cells and/or gestatingthe cells and/or nuclei in surrogate mothers.

In one embodiment, only male non-human animals that are heterozygous forthe replacement at the heavy chain locus are bred to female non-humananimals. In a specific embodiment, the female non-human animals arehomozygous, heterozygous, or wild type with respect to a replaced heavychain locus.

In one embodiment, the non-human animals further comprise a replacementof λ and/or κ light chain variable sequences at an endogenousimmunoglobulin light chain locus with heterologous immunoglobulin lightchain sequences. In one embodiment, the heterologous immunoglobulinlight chain sequences are human immunoglobulin λ and/or κ light chainvariable sequences.

In one embodiment, the non-human animal further comprises a transgene ata locus other than an endogenous immunoglobulin locus, wherein thetransgene comprises a sequence encoding a rearranged or unrearrangedheterologous λ or κ light chain sequence (e.g., unrearranged V_(L) andunrearranged J_(L), or rearranged V_(L)J_(L)) operably linked (forunrearranged) or fused (for rearranged) to an immunoglobulin light chainconstant region sequence. In one embodiment, the heterologous λ or κlight chain sequence is human. In one embodiment, the constant regionsequence is selected from rodent, human, and non-human primate. In oneembodiment, the constant region sequence is selected from mouse, rat,and hamster. In one embodiment, the transgene comprises anon-immunoglobulin promoter that drives expression of the light chainsequences. In a specific embodiment, the promoter is a transcriptionallyactive promoter. In a specific embodiment, the promoter is a ROSA26promoter.

In one aspect, a method for making a genetically modified non-humananimal is provided, comprising inserting a non-human nucleotide sequencethat comprises a non-human immunoglobulin gene segment in the genome ofthe animal for a first modification, wherein the insertion maintains anendogenous ADAM6 gene, then rendering the endogenous immunoglobulinheavy chain locus of the non-human animal non-functional for a secondmodification. In one embodiment, the first modification is performedupstream of an endogenous immunoglobulin heavy chain constant regiongene and the second modification is performed to invert, translocate, orplace out of operable linkage the endogenous immunoglobulin heavy chainlocus such that the endogenous immunoglobulin heavy chain locus isincapable of rearranging to encode a functional heavy chain variableregion.

In one aspect, a method for making a genetically modified non-humananimal is provided, comprising replacing a non-human nucleotide sequencethat comprises a non-human immunoglobulin gene segment and a non-humanADAM6 (or ortholog or homolog or fragment thereof functional in a malenon-human animal) nucleotide sequence with a sequence comprising a humanimmunoglobulin gene segment to form a first chimeric locus, theninserting a sequence comprising a non-human ADAM6-encoding sequence (ora sequence encoding an ortholog or homolog or functional fragmentthereof) into the sequence comprising the human immunoglobulin genesegment to form a second chimeric locus.

In one embodiment, the second chimeric locus comprises a humanimmunoglobulin heavy chain variable (V_(H)) gene segment. In oneembodiment, the second chimeric locus comprises a human immunoglobulinlight chain variable (V_(L)) gene segment. In a specific embodiment, thesecond chimeric locus comprises a human V_(H) gene segment or a humanV_(L) gene segment operably linked to a human D_(H) gene segment and ahuman J_(H) gene segment. In a further specific embodiment, the secondchimeric locus is operably linked to a third chimeric locus thatcomprises a human C_(H)1 sequence, or a human C_(H)1 and human hingesequence, fused with a mouse C_(H)2+C_(H)3 sequence.

In one aspect, use of a mouse that comprises an ectopic nucleotidesequence comprising a mouse ADAM6 locus or sequence to make a fertilemale mouse is provided, wherein the use comprises mating the mousecomprising the ectopic nucleotide sequence that comprises the mouseADAM6 locus or sequence to a mouse that lacks a functional endogenousmouse ADAM6 locus or sequence, and obtaining a progeny that is a femalecapable of producing progeny having the ectopic ADAM6 locus or sequenceor that is a male that comprises the ectopic ADAM6 locus or sequence,and the male exhibits a fertility that is approximately the same as afertility exhibited by a wild-type male mouse.

In one aspect, use of a mouse as described herein to make animmunoglobulin variable region nucleotide sequence is provided.

In one aspect, use of a mouse as described herein to make a fully humanFab or a fully human F(ab)₂ is provided.

In one aspect, use of a mouse as described herein to make animmortalized cell line is provided.

In one aspect, use of a mouse as described herein to make a hybridoma orquadroma is provided.

In one aspect, use of a mouse as described herein to make a phagelibrary containing human heavy chain variable regions and human lightchain variable regions is provided.

In one embodiment, the human heavy chain variable regions are derivedfrom a human V_(H)1-69 gene segment that comprises a sequence selectedfrom SEQ ID NO: 37, SEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ IDNO: 43, SEQ ID NO: 45, SEQ ID NO: 47, SEQ ID NO: 49, SEQ ID NO: 51, SEQID NO: 53, SEQ ID NO: 55, SEQ ID NO: 57 and SEQ ID NO: 59.

In one embodiment, the human heavy chain variable regions are derivedfrom a human V_(H)1-69 gene segment that comprises a sequence selectedfrom SEQ ID NO: 38, SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 44, SEQ IDNO: 46, SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, SEQ ID NO: 54, SEQID NO: 56, SEQ ID NO: 58, SEQ ID NO: 60 and SEQ ID NO: 62.

In one embodiment, the human heavy chain variable regions are allderived from a human V_(H)1-2 gene segment that comprises a sequenceselected from SEQ ID NO: 63, SEQ ID NO: 65, SEQ ID NO: 67, SEQ ID NO: 69and SEQ ID NO: 71.

In one embodiment, the human heavy chain variable regions are derivedfrom a human V_(H)1-2 gene segment that comprises a sequence selectedfrom SEQ ID NO: 64, SEQ ID NO: 66, SEQ ID NO: 68, SEQ ID NO: 70 and SEQID NO: 72.

In one aspect, use of a mouse as described herein to generate a variableregion sequence for making a human antibody is provided, comprising (a)immunizing a mouse as described herein with an antigen of interest, (b)isolating a lymphocyte from the immunized mouse of (a), (c) exposing thelymphocyte to one or more labeled antibodies, (d) identifying alymphocyte that is capable of binding to the antigen of interest, and(e) amplifying one or more variable region nucleic acid sequence fromthe lymphocyte thereby generating a variable region sequence.

In one embodiment, the lymphocyte is derived from the spleen of themouse. In one embodiment, the lymphocyte is derived from a lymph node ofthe mouse. In one embodiment, the lymphocyte is derived from the bonemarrow of the mouse.

In one embodiment, the labeled antibody is a fluorophore-conjugatedantibody. In one embodiment, the one or more fluorophore-conjugatedantibodies are selected from an IgM, an IgG, and/or a combinationthereof.

In one embodiment, the lymphocyte is a B cell.

In one embodiment, the one or more variable region nucleic acid sequencecomprises a heavy chain variable region sequence. In one embodiment, theone or more variable region nucleic acid sequence comprises a lightchain variable region sequence. In a specific embodiment, the lightchain variable region sequence is an immunoglobulin κ light chainvariable region sequence. In one embodiment, the one or more variableregion nucleic acid sequence comprises a heavy chain and a κ light chainvariable region sequence.

In one embodiment, use of a mouse as described herein to generate aheavy and a κ light chain variable region sequence for making a humanantibody is provided, comprising (a) immunizing a mouse as describedherein with an antigen of interest, (b) isolating the spleen from theimmunized mouse of (a), (c) exposing B lymphocytes from the spleen toone or more labeled antibodies, (d) identifying a B lymphocyte of (c)that is capable of binding to the antigen of interest, and (e)amplifying a heavy chain variable region nucleic acid sequence and a κlight chain variable region nucleic acid sequence from the B lymphocytethereby generating the heavy chain and κ light chain variable regionsequences.

In one embodiment, use of a mouse as described herein to generate aheavy and a κ light chain variable region sequence for making a humanantibody is provided, comprising (a) immunizing a mouse as describedherein with an antigen of interest, (b) isolating one or more lymphnodes from the immunized mouse of (a), (c) exposing B lymphocytes fromthe one or more lymph nodes to one or more labeled antibodies, (d)identifying a B lymphocyte of (c) that is capable of binding to theantigen of interest, and (e) amplifying a heavy chain variable regionnucleic acid sequence and a κ light chain variable region nucleic acidsequence from the B lymphocyte thereby generating the heavy chain and κlight chain variable region sequences.

In one embodiment, use of a mouse as described herein to generate aheavy and a κ light chain variable region sequence for making a humanantibody is provided, comprising (a) immunizing a mouse as describedherein with an antigen of interest, (b) isolating bone marrow from theimmunized mouse of (a), (c) exposing B lymphocytes from the bone marrowto one or more labeled antibodies, (d) identifying a B lymphocyte of (c)that is capable of binding to the antigen of interest, and (e)amplifying a heavy chain variable region nucleic acid sequence and a κlight chain variable region nucleic acid sequence from the B lymphocytethereby generating the heavy chain and κ light chain variable regionsequences. In various embodiments, the one or more labeled antibodiesare selected from an IgM, an IgG, and/or a combination thereof.

In various embodiments, the antigen of interest is a pathogen thatafflicts human subjects including, e.g., a viral antigen. Exemplaryviral pathogens include, e.g., mainly those of the families ofAdenoviridae, bacteria Picornaviridae, Herpesviridae, Hepadnaviridae,Flaviviridae, Retroviridae, Orthomyxoviridae, Paramyxoviridae,Papovaviridae, Polyomavirus, Rhabdoviridae, and Togaviridae. Suchexemplary viruses typically range between 20-300 nanometers in length.In various embodiments, the antigen of interest is a viral antigenselected from a hepatitis virus (e.g., HCV, HBV, etc.), a humanimmunodeficiency virus (HIV), or an influenza virus.

In various embodiments, use of a mouse as described herein to generate aheavy and κ light chain variable region sequence for making a humanantibody is provided, further comprising fusing the amplified heavy andlight chain variable region sequences to human heavy and light chainconstant region sequences, expressing the fused heavy and light chainsequences in a cell, and recovering the expressed heavy and light chainsequences thereby generating a human antibody.

In various embodiments, the human heavy chain constant regions areselected from IgM, IgD, IgA, IgE and IgG. In various specificembodiments, the IgG is selected from an IgG1, an IgG2, an IgG3 and anIgG4. In various embodiments, the human heavy chain constant regioncomprises a CHI, a hinge, a C_(H)2, a C_(H)3, a C_(H)4, or a combinationthereof. In various embodiments, the light chain constant region is animmunoglobulin κ constant region. In various embodiments, the cell isselected from a HeLa cell, a DU145 cell, a Lncap cell, a MCF-7 cell, aMDA-MB-438 cell, a PC3 cell, a T47D cell, a THP-1 cell, a U87 cell, aSHSY5Y (human neuroblastoma) cell, a Saos-2 cell, a Vero cell, a CHOcell, a GH3 cell, a PC12 cell, a human retinal cell (e.g., a PER.C6™cell), and a MC3T3 cell. In a specific embodiment, the cell is a CHOcell.

In one aspect, a method for generating a reverse-chimeric rodent-humanantibody specific against an antigen of interest is provided, comprisingthe steps of immunizing a mouse as described herein with the antigen,isolating at least one cell from the mouse producing a reverse-chimericmouse-human antibody specific against the antigen, culturing at leastone cell producing the reverse-chimeric mouse-human antibody specificagainst the antigen, and obtaining said antibody.

In one embodiment, the reverse-chimeric mouse-human antibody comprises ahuman heavy chain variable domain fused with a mouse or rat heavy chainconstant gene, and a human light chain variable domain fused with amouse or rat or human light chain constant gene. In a specificembodiment, the human heavy chain variable domain contains a rearrangedhuman V_(H)1-69 or human V_(H)1-2 gene segment.

In one embodiment, culturing at least one cell producing thereverse-chimeric rodent-human antibody specific against the antigen isperformed on at least one hybridoma cell generated from the at least onecell isolated from the mouse.

In one aspect, a method for generating a fully human antibody specificagainst an antigen of interest is provided, comprising the steps ofimmunizing a mouse as described herein with the antigen, isolating atleast one cell from the mouse producing a reverse-chimeric rodent-humanantibody specific against the antigen, generating at least one cellproducing a fully human antibody derived from the reverse-chimericrodent-human antibody specific against the antigen, and culturing atleast one cell producing the fully human antibody, and obtaining saidfully human antibody.

In various embodiments, the at least one cell isolated from the mouseproducing a reverse-chimeric rodent-human antibody specific against theantigen is a splenocyte or a B cell.

In various embodiments, the antibody is a monoclonal antibody.

In various embodiments, the antibody comprises a heavy chain variabledomain that contains a rearranged human V_(H)1-69 or human V_(H)1-2 genesegment.

In various embodiments, immunization with the antigen of interest iscarried out with protein, DNA, a combination of DNA and protein, orcells expressing the antigen.

In one aspect, use of a mouse as described herein to make a nucleic acidsequence encoding an immunoglobulin variable region or fragment thereofis provided. In one embodiment, the nucleic acid sequence is used tomake a human antibody or antigen-binding fragment thereof. In oneembodiment, the mouse is used to make an antigen-binding proteinselected from an antibody, a multi-specific antibody (e.g., abi-specific antibody), an scFv, a bi-specific scFv, a diabody, atriabody, a tetrabody, a V-NAR, a V_(HH), a V_(L), a F(ab), a F(ab)₂, aDVD (i.e., dual variable domain antigen-binding protein), a an SVD(i.e., single variable domain antigen-binding protein), or a bispecificT-cell engager (BiTE).

In one aspect, a method for making a human antigen-binding protein isprovided, comprising exposing a genetically engineered non-human animalas described herein to an antigen of interest, allowing the non-humananimal to mount an immune response to the antigen, obtaining from thenon-human animal a heavy chain variable domain nucleic acid sequenceencoding a human heavy chain variable domain that specifically binds theantigen of interest, fusing the heavy chain variable domain nucleic acidsequence to a human constant region sequence, and expressing in amammalian cell an antibody comprising the human heavy chain variabledomain sequence and the human constant region sequence. In oneembodiment, the mammalian cell is a CHO cell. In one embodiment thenon-human animal comprises a human V_(H) gene segment repertoire thatconsists essentially of a single human V_(H) gene segment, optionallypresent in two or more polymorphic variants thereof, operably linked toone or more human D and/or J segments. In one embodiment, the humanV_(H) gene segment repertoire is at an endogenous non-human V_(H) genesegment locus. In one embodiment, the human V_(H) gene segmentrepertoire is at a locus that is not an endogenous V_(H) gene segmentlocus. In one embodiment, the human V_(H) gene segment rearranges with ahuman D segment and a human J segment to form a rearranged human VDJgene operably linked to a constant region sequence, wherein the constantregion sequence is selected from a human sequence and a rodent sequence(e.g., a mouse or rat or hamster sequence). In one embodiment, theconstant region sequence comprises a sequence selected from a C_(H)1, ahinge, a C_(H)2, a C_(H)3, and a combination thereof; in a specificembodiment, the constant region sequence comprises a C_(H)1, a hinge, aC_(H)2, and a C_(H)3. In one embodiment, the human variable domain andthe constant sequence are expressed in the mammalian cell with a cognatehuman light chain variable domain obtained from the same mouse (e.g.,sequence obtained from the same B cell as the human variable domainsequence); in one embodiment the sequence encoding the human light chainvariable domain obtained from the mouse is then fused with a sequenceencoding a human light chain constant sequence, and the light chainsequence and the heavy chain sequence are expressed in the mammaliancell.

In one aspect, a method for making an antibody heavy chain variabledomain that binds an antigen of interest is provided, comprisingexpressing in a single cell (a) a first V_(H) sequence of an immunizednon-human animal as described herein, wherein the first V_(H) sequenceis fused with a C_(H) gene sequence; and (b) a V_(L) gene sequence of animmunized non-human animal as described herein, wherein the V_(L) genesequence is fused with a human C_(L) gene sequence; maintaining the cellunder conditions sufficient to express an antibody; and, isolating theantibody heavy chain variable domain. In one embodiment, the V_(L) genesequence is cognate with the first V_(H) sequence.

In one embodiment, the cell comprises a second V_(H) gene sequence of animmunized non-human animal as described herein, wherein the second V_(H)gene sequence is fused with a C_(H) gene sequence, wherein the firstV_(H) gene sequence encodes a V_(H) domain that specifically binds afirst epitope, and the second V_(H) gene sequence encodes a V_(H) domainthat specifically binds a second epitope, wherein the first epitope andthe second epitope are not identical.

In one embodiment, the constant region sequences are all human constantregion sequences.

In one aspect, a method for making a human bispecific antibody isprovided, comprising making the bispecific antibody using human variableregion gene sequences of B cells of a non-human animal as describedherein.

In one embodiment, the method comprises (a) identifying a clonallyselected lymphocyte of the non-human animal, wherein the non-humananimal has been exposed to an antigen of interest and allowed to developan immune response to the antigen of interest, and wherein thelymphocyte expresses an antibody that specifically binds the antigen ofinterest, (b) obtaining from the lymphocyte or the antibody a nucleotidesequence that encodes a human heavy chain variable region thatspecifically binds the antigen of interest, and (c) employing thenucleotide sequence that encodes the human heavy chain variable regionthat specifically binds the antigen of interest in making the bispecificantibody. In a specific embodiment, the human heavy chain variableregion comprises a rearranged V_(H)1-2 or V_(H)1-69 gene segment.

In one embodiment, steps (a) through (c) are performed a first time fora first antigen of interest to generate a first human heavy chainvariable region sequence, and steps (a) through (c) are performed asecond time for a second antigen of interest to generate a second humanheavy chain variable region sequence, and wherein the first human heavychain variable region sequence is expressed fused with a first humanheavy chain constant region to form a first human heavy chain, thesecond human heavy chain variable region sequence is expressed fusedwith a second human heavy chain constant region to form a second humanheavy chain, wherein the first and the second human heavy chains areexpressed in the presence of a single human light chain expressed from arearranged human Vκ1-39 or a human Vκ3-20 gene segment. In a specificembodiment, the single human light chain comprises a germline sequence.

In one embodiment, the method comprises (a) cloning heavy chain variableregions from B cells of a non-human animal as described herein which hasbeen exposed to a first antigen of interest, and the same non-humananimal, or a different non-human animal which is genetically the sameand has been exposed to a second antigen of interest; and (b) expressingin a cell the heavy chain variable regions of (a) with the same heavychain constant region and the same light chain to make a bispecificantibody.

In one aspect, a use of a non-human animal as described herein isprovided, to obtain a nucleic acid sequence that encodes a human heavychain variable domain. In one embodiment, the heavy chain variabledomain comprises a rearranged human V_(H) gene segment selected fromV_(H)1-2 and V_(H)1-69.

In one aspect, a use of a non-human animal as described herein isprovided, to obtain a cell that encodes a human heavy chain variabledomain. In one embodiment, the heavy chain variable domain comprises arearranged human V_(H) gene segment selected from V_(H)1-2 andV_(H)1-69.

In one aspect, use of a non-human animal as described herein to make ahuman antibody variable domain is provided. In one aspect, use of anon-human animal as described herein to make a human antibody isprovided. In one embodiment, the human antibody is a human bispecificantibody. In various embodiments, the variable domain and/or theantibody comprises a rearranged human V_(H) gene segment selected fromV_(H)1-2 and V_(H)1-69.

In one aspect, use of a non-human animal as described herein is providedto select a human immunoglobulin heavy chain variable domain. In oneembodiment, the heavy chain variable domain comprises a rearranged humanV_(H) gene segment selected from V_(H)1-2 and V_(H)1-69.

In one aspect, use of a mouse as described herein to introduce anectopic ADAM6 sequence into a mouse that lacks a functional endogenousmouse ADAM6 sequence is provided, wherein the use comprises mating amouse as described herein with the mouse that lacks the functionalendogenous mouse ADAM6 sequence.

In one aspect, use of genetic material from a mouse as described hereinto make a mouse having an ectopic ADAM6 sequence is provided. In oneembodiment, the use comprises nuclear transfer using a nucleus of a cellof a mouse as described herein. In one embodiment, the use comprisescloning a cell of a mouse as described herein to produce an animalderived from the cell. In one embodiment, the use comprises employing asperm or an egg of a mouse as described herein in a process for making amouse comprising the ectopic ADAM6 sequence.

In one aspect, a method for making a fertile male mouse comprising amodified immunoglobulin heavy chain locus is provided, comprisingfertilizing a first mouse germ cell that comprises a modification of anendogenous immunoglobulin heavy chain locus with a second mouse germcell that comprises an ADAM6 gene or ortholog or homolog or fragmentthereof that is functional in a male mouse; forming a fertilized cell;allowing the fertilized cell to develop into an embryo; and, gestatingthe embryo in a surrogate to obtain a mouse.

In one embodiment, the fertilization is achieved by mating a male mouseand a female mouse. In one embodiment, the female mouse comprises theADAM6 gene or ortholog or homolog or fragment thereof. In oneembodiment, the male mouse comprises the ADAM6 gene or ortholog orhomolog or fragment thereof.

In one aspect, use of a nucleic acid sequence encoding a mouse ADAM6protein or an ortholog or homolog thereof or a functional fragment ofthe corresponding ADAM6 protein for restoring or enhancing the fertilityof a mouse having a genome comprising a modification of animmunoglobulin heavy chain locus is provided, wherein the modificationreduces or eliminates endogenous ADAM6 function.

In one embodiment, the nucleic acid sequence is integrated into thegenome of the mouse at an ectopic position. In one embodiment, thenucleic acid sequence is integrated into the genome of the mouse at anendogenous immunoglobulin locus. In a specific embodiment, theendogenous immunoglobulin locus is a heavy chain locus. In oneembodiment, the nucleic acid sequence is integrated into the genome ofthe mouse at a position other than an endogenous immunoglobulin locus.

In one aspect, use of the mouse as described herein for the manufactureof a medicament (e.g., an antigen-binding protein), or for themanufacture of a sequence encoding a variable sequence of a medicament(e.g., an antigen-binding protein), for the treatment of a human diseaseor disorder is provided. In one embodiment, the variable sequence of amedicament comprises a polymorphic human V_(H) gene segment. In oneembodiment, the variable sequence of a medicament comprises a humanV_(H)1-69 gene segment. In one embodiment, the variable sequence of amedicament comprises a human V_(H)1-2 gene segment.

In one aspect, a nucleic acid construct encoding an immunoglobulinvariable domain made in a mouse as described herein is provided. In oneembodiment, the variable domain is a heavy chain variable domain. In aspecific embodiment, the heavy chain variable domain comprises a humanV_(H) gene segment selected from V_(H)1-2, V_(H)1-69, V_(H)2-26,V_(H)2-70, or V_(H)3-23. In another specific embodiment, the heavy chainvariable domain comprises a human V_(H)1-2 gene segment. In anotherspecific embodiment, the heavy chain variable domain comprises a humanV_(H)1-69 gene segment.

In one embodiment, the variable domain is a light chain variable domain.In a specific embodiment, the variable domain is a κ light chainvariable domain that is cognate with a human heavy chain variable domainthat comprises a rearranged human V_(H)1-69 gene segment. In a specificembodiment, the variable domain is a κ light chain variable domain thatis cognate with a human heavy chain variable domain that comprises arearranged human V_(H)1-2 gene segment.

In one aspect, use of a mouse as described herein to make a nucleic acidconstruct encoding a human immunoglobulin variable domain is provided.In one embodiment, the variable domain is a light chain variable domain.In one embodiment, the variable domain is a κ light chain variabledomain that comprises a rearranged human Vκ gene segment selected fromVκ4-1, Vκ5-2, Vκ7-3, Vκ2-4, Vκ1-5, Vκ1-6, Vκ3-7, Vκ1-8, Vκ1-9, Vκ2-10,Vκ3-11, Vκ1-12, Vκ1-13, Vκ2-14, Vκ3-15, Vκ1-16, Vκ1-17, Vκ2-18, Vκ2-19,Vκ3-20, Vκ6-21, Vκ1-22, Vκ1-23, Vκ2-24, Vκ3-25, Vκ2-26, Vκ1-27, Vκ2-28,Vκ2-29, Vκ2-30, Vκ3-31, Vκ1-32, Vκ1-33, Vκ3-34, Vκ1-35, Vκ2-36, Vκ1-37,Vκ2-38, Vκ1-39, and Vκ2-40.

In one embodiment, the variable domain is a heavy chain variable domain.In a specific embodiment, the heavy chain variable domain comprises arearranged human V_(H) gene segment selected from V_(H)1-2, V_(H)1-69,V_(H)2-26, V_(H)2-70, or V_(H)3-23. In a specific embodiment, the heavychain variable domain comprises a rearranged human V_(H)1-69 genesegment. In a specific embodiment, the heavy chain variable domaincomprises a rearranged human V_(H)1-2 gene segment.

In one aspect, use of a mouse as described herein to make a humanimmunoglobulin variable domain is provided. In one embodiment, thevariable domain is a light chain variable domain. In one embodiment, thevariable domain is a κ light chain variable domain that comprises arearranged human Vκ gene segment selected from Vκ4-1, Vκ5-2, Vκ7-3,Vκ2-4, Vκ1-5, Vκ1-6, Vκ3-7, Vκ1-8, Vκ1-9, Vκ2-10, Vκ3-11, Vκ1-12,Vκ1-13, Vκ2-14, Vκ3-15, Vκ1-16, Vκ1-17, Vκ2-18, Vκ2-19, Vκ3-20, Vκ6-21,Vκ1-22, Vκ1-23, Vκ2-24, Vκ3-25, Vκ2-26, Vκ1-27, Vκ2-28, Vκ2-29, Vκ2-30,Vκ3-31, Vκ1-32, Vκ1-33, Vκ3-34, Vκ1-35, Vκ2-36, Vκ1-37, Vκ2-38, Vκ1-39,and Vκ2-40.

In one embodiment, the variable domain is a heavy chain variable domain.In a specific embodiment, the heavy chain variable domain comprises arearranged human V_(H) gene segment selected from V_(H)1-2, V_(H)-69,V_(H)2-26, V_(H)2-70, or V_(H)3-23. In a specific embodiment, the heavychain variable domain comprises a rearranged human V_(H)1-69 genesegment. In a specific embodiment, the heavy chain variable domaincomprises a rearranged human V_(H)1-2 gene segment.

The various aspects and embodiments are capable of use together, unlessexpressly noted otherwise or the context clearly prohibits use together.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows a general illustration, not to scale, of a series oftargeting and molecular engineering steps employed to make a targetingvector for construction of a modified heavy chain locus containing asingle human V_(H)1-69 gene segment, twenty-seven human D_(H) and sixhuman J_(H) gene segments at an endogenous immunoglobulin heavy chainlocus.

FIG. 2 shows a general illustration, not to scale, of a series oftargeting and molecular engineering steps employed to make a targetingvector for construction of a modified heavy chain locus containing asingle human V_(H)1-2 gene segment, twenty-seven human D_(H) and sixhuman J_(H) gene segments at an endogenous immunoglobulin heavy chainlocus.

FIG. 3 shows a general illustration, not to scale, of a series oftargeting and molecular engineering steps employed to make a targetingvector for construction of a modified heavy chain locus containing asingle human V_(H)1-69 gene segment, twenty-seven human D_(H), six humanJ_(H) gene segments and an ectopic genomic fragment encoding mouse ADAM6at an endogenous immunoglobulin heavy chain locus.

FIG. 4 shows a general illustration, not to scale, of a series oftargeting and molecular engineering steps employed to make a targetingvector for construction of a modified heavy chain locus containing asingle human V_(H)1-2 gene segment, twenty-seven human D_(H), six humanJ_(H) gene segments and an ectopic genomic fragment encoding mouse ADAM6at an endogenous immunoglobulin heavy chain locus.

FIG. 5 shows the nucleotide alignment of the second exon for each ofthirteen reported alleles for the human V_(H)1-69 gene. Lower case basesindicate germline nucleotide differences among the alleles.Complementary determining regions (CDRs) are indicated with boxes aroundthe sequence. Dashes indicate artificial gaps for proper sequencealignment. V_(H)1-69*01 (SEQ ID NO: 37); V_(H)1-69*02 (SEQ ID NO: 39);V_(H)1-69*03 (SEQ ID NO: 41); V_(H)1-6904 (SEQ ID NO: 43); V_(H)1-69*05(SEQ ID NO: 45); V_(H)1-69*06 (SEQ ID NO: 47); V_(H)1-69*07 (SEQ ID NO:49); V_(H)1-69*08 (SEQ ID NO: 51); V_(H)1-69*09 (SEQ ID NO: 53);V_(H)1-69*10 (SEQ ID NO: 55); V_(H)1-69*11 (SEQ ID NO: 57); V_(H)1-69*12(SEQ ID NO: 59); V_(H)1-69*13 (SEQ ID NO: 61).

FIG. 6 shows the protein alignment of the mature heavy chain variablegene sequence for each of thirteen reported alleles for the humanV_(H)1-69 gene. Lower case amino acids indicate germline differencesamong the alleles. Complementary determining regions (CDRs) areindicated with boxes around the sequence. Dashes indicate artificialgaps for proper sequence alignment. V_(H)1-69*01 (SEQ ID NO: 38);V_(H)1-69*02 (SEQ ID NO: 40); V_(H)1-69*03 (SEQ ID NO: 42); V_(H)1-69*04(SEQ ID NO: 44); V_(H)1-69*05 (SEQ ID NO: 46); V_(H)1-69*06 (SEQ ID NO:48); V_(H)1-69*07 (SEQ ID NO: 50); V_(H)1-69*08 (SEQ ID NO: 52);V_(H)1-69*09 (SEQ ID NO: 54); V_(H)1-69*10 (SEQ ID NO: 56); V_(H)1-69*11(SEQ ID NO: 58); V_(H)1-69*12 (SEQ ID NO: 60); V_(H)1-69*13 (SEQ ID NO:62).

FIG. 7 shows a percent identity/percent similarity matrix for thealigned protein sequences of the mature variable gene for each ofthirteen reported alleles for the human V_(H)1-69 gene. Percent identityamong the V_(H)1-69 alleles is indicated above the shaded boxes andpercent similarity is indicated below the shaded boxes. Scores forpercent identity and percent similarity were scored by a ClustaiW(v1.83) alignment tool using MacVector software (MacVector, Inc., NorthCarolina).

FIG. 8 shows the nucleotide alignment of the second exon for each offive reported alleles for the human V_(H)1-2 gene. Lower case basesindicate germline nucleotide differences among the alleles.Complementary determining regions (CDRs) are indicated with boxes aroundthe sequence. Dashes indicate artificial gaps for proper sequencealignment. V_(H)1-2*01 (SEQ ID NO: 63); V_(H)1-2*02 (SEQ ID NO: 65);V_(H)1-2*03 (SEQ ID NO: 67); V_(H)1-2*04 (SEQ ID NO: 69); V_(H)1-2*05(SEQ ID NO: 71).

FIG. 9 shows the protein alignment of the mature heavy chain variablegene sequence for each of the five reported alleles for the humanV_(H)1-2 gene. Lower case amino acids indicate germline differencesamong the alleles. Complementary determining regions (CDRs) areindicated with boxes around the sequence. Dashes indicate artificialgaps for proper sequence alignment. V_(H)1-2*01 (SEQ ID NO: 64);V_(H)1-2*02 (SEQ ID NO: 66); V_(H)1-2*03 (SEQ ID NO: 68); V_(H)1-2*04(SEQ ID NO: 70); V_(H)1-2*05 (SEQ ID NO: 72).

FIG. 10 shows a percent identity/percent similarity matrix for thealigned protein sequences of the mature variable gene for each of fivereported alleles for the human V_(H)1-2 gene. Percent identity among theV_(H)1-2 alleles is indicated above the shaded boxes and percentsimilarity is indicated below the shaded boxes. Scores for percentidentity and percent similarity were scored by a ClustalW (v1.83)alignment tool using MacVector software (MacVector, Inc., NorthCarolina).

DETAILED DESCRIPTION

This invention is not limited to particular methods, and experimentalconditions described, as such methods and conditions may vary. It isalso to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting, since the scope of the present invention is defined bythe claims.

Unless defined otherwise, all terms and phrases used herein include themeanings that the terms and phrases have attained in the art, unless thecontrary is clearly indicated or clearly apparent from the context inwhich the term or phrase is used. Although any methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, particular methods andmaterials are now described. All publications mentioned are herebyincorporated by reference.

The phrase “substantial” or “substantially” when used to refer to anamount of gene segments (e.g., “substantially all” V gene segments)includes both functional and non functional gene segments and include,in various embodiments, e.g., 80% or more, 85% or more, 90% or more, 95%or more 96% or more, 97% or more, 98% or more, or 99% or more of allgene segments; in various embodiments, “substantially all” gene segmentsincludes, e.g., at least 95%, 96%, 97%, 98%, or 99% of functional (i.e.,non-pseudogene) gene segments.

The term “replacement” includes wherein a DNA sequence is placed into agenome of a cell in such a way as to replace a sequence within thegenome with a heterologous sequence (e.g., a human sequence in a mouse),at the locus of the genomic sequence. The DNA sequence so placed mayinclude one or more regulatory sequences that are part of source DNAused to obtain the sequence so placed (e.g., promoters, enhancers, 5′-or 3′-untranslated regions, appropriate recombination signal sequences,etc.). For example, in various embodiments, the replacement is asubstitution of an endogenous sequence for a heterologous sequence thatresults in the production of a gene product from the DNA sequence soplaced (comprising the heterologous sequence), but not expression of theendogenous sequence; the replacement is of an endogenous genomicsequence with a DNA sequence that encodes a protein that has a similarfunction as a protein encoded by the endogenous genomic sequence (e.g.,the endogenous genomic sequence encodes an immunoglobulin gene ordomain, and the DNA fragment encodes one or more human immunoglobulingenes or domains). In various embodiments, an endogenous gene orfragment thereof is replaced with a corresponding human gene or fragmentthereof. A corresponding human gene or fragment thereof is a human geneor fragment that is an ortholog of, a homolog of, or is substantiallyidentical or the same in structure and/or function, as the endogenousgene or fragment thereof that is replaced.

The mouse as a genetic model has been greatly enhanced by transgenic andknockout technologies, which have allowed for the study of the effectsof the directed over-expression or deletion of specific genes. Despiteall of its advantages, the mouse still presents genetic obstacles thatrender it an imperfect model for human diseases and an imperfectplatform to test human therapeutics or make them. First, although about99% of human genes have a mouse homolog (Waterston et al. 2002, Initialsequencing and comparative analysis of the mouse genome, Nature420:520-562), potential therapeutics often fail to cross-react, orcross-react inadequately, with mouse orthologs of the intended humantargets. To obviate this problem, selected target genes can be“humanized,” that is, the mouse gene can be eliminated and replaced bythe corresponding human orthologous gene sequence (e.g., U.S. Pat. Nos.6,586,251, 6,596,541 and 7,105,348, incorporated herein by reference).Initially, efforts to humanize mouse genes by a“knockout-plus-transgenic humanization” strategy entailed crossing amouse carrying a deletion (i.e., knockout) of the endogenous gene with amouse carrying a randomly integrated human transgene (see, e.g., Bril atal., 2006, Tolerance to factor VIII in a transgenic mouse expressinghuman factor VIII cDNA carrying an Arg(593) to Cys substitution, ThrombHaemost 95:341-347; Homanics et al., 2006, Production andcharacterization of murine models of classic and intermediate maplesyrup urine disease, BMC Med Genet 7:33; Jamsai et al., 2006, Ahumanized BAC transgenic/knockout mouse model for HbE/beta-thalassemia,Genomics 88(3):309-15; Pan et al., 2006, Different role for mouse andhuman CD3delta/epsilon heterodimer in preT cell receptor (preTCR)function:human CD3delta/epsilon heterodimer restores the defectivepreTCR function in CD3gamma- and CD3gammadelta-deficient mice, MolImmunol 43:1741-1750). But those efforts were hampered by sizelimitations; conventional knockout technologies were not sufficient todirectly replace large mouse genes with their large human genomiccounterparts. A straightforward approach of direct homologousreplacement, in which an endogenous mouse gene is directly replaced bythe human counterpart gene at the same precise genetic location of themouse gene (i.e., at the endogenous mouse locus), is rarely attemptedbecause of technical difficulties. Until now, efforts at directreplacement involved elaborate and burdensome procedures, thus limitingthe length of genetic material that could be handled and the precisionwith which it could be manipulated.

Exogenously introduced human immunoglobulin transgenes rearrange inprecursor B cells in mice (Alt et al., 1985, Immunoglobulin genes intransgenic mice, Trends Genet 1:231-236). This finding was exploited byengineering mice using the knockout-plus-transgenic approach to expresshuman antibodies (Green et al., 1994, Antigen-specific human monoclonalantibodies from mice engineered with human Ig heavy and light chainYACs, Nat Genet 7:13-21; Lonberg et al., 1994, Antigen-specific humanantibodies from mice comprising four distinct genetic modifications,Nature 368:856-859; Jakobovits et al., 2007, From XenoMouse technologyto panitumumab, the first fully human antibody product from transgenicmice, Nat Biotechnol 25:1134-1143). The mouse immunoglobulin heavy chainand κ light chain loci were inactivated in these mice by targeteddeletion of small but critical portions of each endogenous locus,followed by introducing human immunoglobulin gene loci as randomlyintegrated large transgenes, as described above, or minichromosomes(Tomizuka et al., 2000, Double trans-chromosomic mice: maintenance oftwo individual human chromosome fragments containing Ig heavy and kappaloci and expression of fully human antibodies, PNAS USA 97:722-727).Such mice represented an important advance in genetic engineering; fullyhuman monoclonal antibodies isolated from them yielded promisingtherapeutic potential for treating a variety of human diseases (Gibsonet al., 2006, Randomized phase III trial results of panitumumab, a fullyhuman anti-epidermal growth factor receptor monoclonal antibody, inmetastatic colorectal cancer, Clin Colorectal Cancer 6:29-31; Jakobovitset al., 2007; Kim et al., 2007, Clinical efficacy of zanolimumab(HuMax-CD4): two Phase II studies in refractory cutaneous T-celllymphoma, Blood 109(11):4655-62; Lonberg, 2005, Human antibodies fromtransgenic animals, Nat Biotechnol 23:1117-1125; Maker et al., 2005,Tumor regression and autoimmunity in patients treated with cytotoxic Tlymphocyte-associated antigen 4 blockade and interleukin 2: a phase I/IIstudy, Ann Surg Oncol 12:1005-1016; McClung et al., 2006, Denosumab inpostmenopausal women with low bone mineral density, New Engl J Med354:821-831). But, as discussed above, these mice exhibit compromised Bcell development and immune deficiencies when compared to wild typemice. Such problems potentially limit the ability of the mice to supporta vigorous humoral response and, consequently, generate fully humanantibodies against some antigens. The deficiencies may be due toinefficient functionality due to the random introduction of the humanimmunoglobulin transgenes and resulting incorrect expression due to alack of upstream and downstream control elements (Garrett et al., 2005,Chromatin architecture near a potential 3′ end of the IgH locus involvesmodular regulation of histone modifications during B-Cell developmentand in vivo occupancy at CTCF sites, Mol Cell Biol 25:1511-1525; Maniset al., 2003, Elucidation of a downstream boundary of the 3′ IgHregulatory region, Mol Immunol 39:753-760; Pawlitzky et al., 2006,Identification of a candidate regulatory element within the 5′ flankingregion of the mouse IgH locus defined by pro-B cell-specifichypersensitivity associated with binding of PU.1, Pax5, and E2A, JImmunol 176:6839-6851), inefficient interspecies interactions betweenhuman constant domains and mouse components of the B-cell receptorsignaling complex on the cell surface, which may impair signalingprocesses required for normal maturation, proliferation, and survival ofB cells (Hombach et al., 1990, Molecular components of the B-cellantigen receptor complex of the IgM class, Nature 343:760-762), andinefficient interspecies interactions between soluble humanimmunoglobulins and mouse Fc receptors that might reduce affinityselection (Rao et al., 2002, Differential expression of the inhibitoryIgG Fc receptor FcgammaRIIB on germinal center cells: implications forselection of high-affinity B cells, J Immunol 169:1859-1868) andimmunoglobulin serum concentrations (Brambell et al., 1964, ATheoretical Model of Gamma-Globulin Catabolism, Nature 203:1352-1354;Junghans and Anderson, 1996, The protection receptor for IgG catabolismis the beta2-microglobulin-containing neonatal intestinal transportreceptor, PNAS USA 93:5512-5516; Rao et al., 2002; Hjelm et al., 2006,Antibody-mediated regulation of the immune response, Scand J Immunol64:177-184; Nimmerjahn and Ravetch, 2007, Fc-receptors as regulators ofimmunity, Adv Immunol 96:179-204). These deficiencies can be correctedby in situ humanization of only the variable regions of the mouseimmunoglobulin loci within their natural locations at the endogenousheavy and light chain loci. This would effectively result in mice thatmake “reverse chimeric” (i.e., human V:mouse C) antibodies which wouldbe capable of normal interactions and selection with the mouseenvironment based on retaining mouse constant regions. Taking thisapproach, a particular version of a humanized locus can be constructedbased on the complexity of the chimeric locus that is desired. Furthersuch reverse chimeric antibodies may be readily reformatted into fullyhuman antibodies for therapeutic purposes.

Genetically modified animals that comprise an insertion or a replacementat the endogenous immunoglobulin heavy chain locus with heterologous(e.g., from another species) immunoglobulin sequences can be made inconjunction with insertions or replacements at endogenous immunoglobulinlight chain loci or in conjunction with immunoglobulin light chaintransgenes (e.g., chimeric immunoglobulin light chain transgenes orfully human fully mouse, etc.). The species from which the heterologousimmunoglobulin heavy chain sequences are derived can vary widely; aswith immunoglobulin light chain sequences employed in immunoglobulinlight chain sequence replacements or immunoglobulin light chaintransgenes. Exemplary heterologous immunoglobulin heavy chain sequencesinclude human sequences.

Immunoglobulin variable region nucleic acid sequences, e.g., V, D,and/or J segments, are in various embodiments obtained from a human or anon-human animal. Non-human animals suitable for providing V, D, and/orJ segments include, for example bony fish, cartilaginous fish such assharks and rays, amphibians, reptiles, mammals, birds (e.g., chickens).Non-human animals include, for example, mammals. Mammals include, forexample, non-human primates, goats, sheep, pigs, dogs, bovine (e.g.,cow, bull, buffalo), deer, camels, ferrets and rodents and non-humanprimates (e.g., chimpanzees, orangutans, gorillas, marmosets, rhesusmonkeys baboons). Suitable non-human animals are selected from therodent family including rats, mice, and hamsters. In one embodiment, thenon-human animals are mice. As clear from the context, various non-humananimals can be used as sources of variable domains or variable regiongene segments (e.g., sharks, rays, mammals, e.g., camels, rodents suchas mice and rats).

According to the context, non-human animals are also used as sources ofconstant region sequences to be used in connection with variablesequences or segments, for example, rodent constant sequences can beused in transgenes operably linked to human or non-human variablesequences (e.g., human or non-human primate variable sequences operablylinked to, e.g., rodent, e.g., mouse or rat or hamster, constantsequences). Thus, in various embodiments, human V, D, and/or J segmentsare operably linked to rodent (e.g., mouse or rat or hamster) constantregion gene sequences. In some embodiments, the human V, D, and/or Jsegments (or one or more rearranged VDJ or VJ genes) are operably linkedor fused to a mouse, rat, or hamster constant region gene sequence in,e.g., a transgene integrated at a locus that is not an endogenousimmunoglobulin locus.

In a specific embodiment, a mouse is provided that comprises areplacement of V_(H), D_(H), and J_(H) gene segments at an endogenousimmunoglobulin heavy chain locus with a single human V_(H), one or moreD_(H), and one or more J_(H) gene segments, wherein the single humanV_(H), One or more D_(H), and one or more J_(H) gene segments areoperably linked to an endogenous immunoglobulin heavy chain gene;wherein the mouse comprises a transgene at a locus other than anendogenous immunoglobulin locus, wherein the transgene comprises anunrearranged or rearranged human V_(L) and human J_(L) gene segmentoperably linked to a mouse or rat or human constant region. In variousembodiments, the single human V_(H) gene segment is a polymorphic genesegment. In one embodiment, the single human V_(H) gene segment is ahuman V_(H)1-69 gene segment or a human V_(H)1-2 gene segment.

A method for an in situ genetic replacement of the mouse germlineimmunoglobulin heavy chain variable gene locus with a restricted humangermline immunoglobulin heavy chain locus and replacement of the mousegermline immunoglobulin κ light chain variable gene loci with humangermline immunoglobulin κ light chain loci, while maintaining theability of the mice to generate offspring, is described. Specifically,the precise replacement of six megabases of both the mouse heavy chainand κ light chain immunoglobulin variable gene loci with humanimmunoglobulin heavy and κ light chain sequences, while leaving themouse constant regions intact, is described. As a result, mice have beencreated that have a precise replacement of their entire germlineimmunoglobulin variable repertoire with human germline immunoglobulinvariable sequences, while maintaining mouse constant regions. The humanvariable regions are linked to mouse constant regions to form chimerichuman-mouse immunoglobulin loci that rearrange and express atphysiologically appropriate levels. The antibodies expressed are“reverse chimeras,” i.e., they comprise human variable region sequencesand mouse constant region sequences.

The genetically modified mice described herein exhibit a fullyfunctional humoral immune system and provide a plentiful source ofnaturally affinity-matured human immunoglobulin variable regionsequences for making pharmaceutically acceptable antibodies and otherantigen-binding proteins that are effective for combating pathogenicantigens, e.g., viral antigens.

The engineering of human immunoglobulin sequences in the genome of amouse, even at precise locations, e.g., at the endogenous mouseimmunoglobulin loci, may present certain challenges due to divergentevolution of the immunoglobulin loci between mouse and man. For example,intergenic sequences interspersed within the immunoglobulin loci are notidentical between mice and humans and, in some circumstances, may not befunctionally equivalent. Differences between mice and humans in theirimmunoglobulin loci can still result in abnormalities in humanized mice,particularly when humanizing or manipulating certain portions ofendogenous mouse immunoglobulin heavy chain loci. Some modifications atmouse immunoglobulin heavy chain loci are deleterious. Deleteriousmodifications can include, for example, loss of the ability of themodified mice to mate and produce offspring. In various embodiments,engineering human immunoglobulin sequences in the genome of a mouseincludes methods that maintain endogenous sequences that when absent inmodified mouse strains are deleterious. Exemplary deleterious effectsmay include inability to propagate modified strains, loss of function ofessential genes, inability to express polypeptides, etc. Suchdeleterious effects may be directly or indirectly related to themodification engineered into the genome of the mouse.

Notwithstanding the near wild-type humoral immune function observed inmice with humanized immunoglobulin loci, there are other challengesencountered when employing a direct replacement of immunoglobulinsequences that is not encountered in some approaches that employrandomly integrated transgenes. Differences in the genetic compositionof the immunoglobulin loci between mice and humans has lead to thediscovery of sequences beneficial for the propagation of mice withreplaced immunoglobulin gene segments. Specifically, mouse ADAM geneslocated within the endogenous immunoglobulin locus are optimally presentin mice with replaced immunoglobulin loci, due to their role infertility.

A precise, in situ replacement of six megabases of the variable regionsof the mouse heavy chain immunoglobulin loci (V_(H)-D_(H)-J_(H)) with arestricted human immunoglobulin heavy chain locus was performed, whileleaving the flanking mouse sequences intact and functional within thehybrid loci, including all mouse constant chain genes and locustranscriptional control regions (FIG. 1 and FIG. 8). Further engineeringsteps were performed to maintain mouse sequences that confer on themouse the ability to mate and produce offspring in a manner comparableto a wild-type mouse (FIG. 9 and FIG. 10). Specifically, a single humanV_(H), 27 D_(H), and six J_(H) gene segments and mouse ADAM6 genes wereintroduced through chimeric BAC targeting vectors into mouse ES cellsusing VELOCIGENE® genetic engineering technology (see, e.g., U.S. Pat.No. 6,586,251 and Valenzuela et al., 2003, High-throughput engineeringof the mouse genome coupled with high-resolution expression analysis,Nat Biotechnol 21:652-659).

Mice With Restricted Immunoglobulin Heavy Chain Variable Gene Segments

Non-human animals comprising immunoglobulin loci that comprise arestricted number of V_(H) genes, and one or more D genes and one ormore J genes, are provided, as are methods of making and using them.When immunized with an antigen of interest, the non-human animalsgenerate B cell populations with antibody variable regions derived onlyfrom the restricted, pre-selected V_(H) gene or set of V_(H) genes(e.g., a pre-selected V_(H) gene and variants thereof). In variousembodiments, non-human animals are provided that generate B cellpopulations that express human antibody variable domains that are humanheavy chain variable domains, along with cognate human light chainvariable domains. In various embodiments, the non-human animalsrearrange human heavy chain variable gene segments and human light chainvariable gene segments from modified endogenous mouse immunoglobulinloci that comprise a replacement or insertion of the non-humanunrearranged variable region sequences with human unrearranged variableregion sequences.

Early work on the organization, structure, and function of theimmunoglobulin genes was done in part on mice with disabled endogenousloci and engineered to have transgenic loci (randomly placed) withpartial human immunoglobulin genes, e.g., a partial repertoire of humanheavy chain genes linked with a human constant gene, randomly insertedinto the genome, in the presence or absence of a human light chaintransgene. Although these mice were somewhat less than optimal formaking useful high affinity antibodies, they facilitated certainfunctional analyses of immunoglobulin loci. Some of these mice had asfew as two or three, or even just a single, heavy chain variable gene.

Mice that express fully human immunoglobulin heavy chains derived from asingle human V_(H)5-51 gene and 10 human D_(H) genes and six human J_(H)genes, with human μ and γ1 constant genes, on a randomly insertedtransgene (and disabled endogenous immunoglobulin loci) have beenreported (Xu and Davis, 2000, Diversity in the CDR3 Region of V_(H) IsSufficient for Most Antibody Specificities, Immunity 13:37-45). Thefully human immunoglobulin heavy chains of these mice are mostlyexpressed with one of just two fully mouse λ light chains derived fromthe endogenous mouse λ light chain locus (Vλ1-Jλ1 or Vλ2-Jλ2 only), andcan express no κ light chain (the mice are Igκ^(−/−)). These miceexhibit severely abnormal dysfunction in B cell development and antibodyexpression. B cell numbers are reportedly 5-10% of wild-type, IgM levels5-10% of wild-type, and IgG1 levels are only 0.1-1% of wild-type. Theobserved IgM repertoire revealed highly restricted junctional diversity.The fully human heavy chains display largely identical CDR3 lengthacross antigens, the same J_(H) (J_(H)2) usage across antigens, and aninitial junctional Q residue, thus reflecting a certain lack of CDR3diversity. The fully mouse λ light chains nearly all had a W96Lsubstitution in Jλ1 as initial junctional residue. The mice arereportedly unable to generate any antibodies against bacterialpolysaccharide. Because the human variable domains couple with mouselight chains, the utility of the human variable regions is highlylimited.

Other mice that have just a single human V_(H)3-23 gene, human D_(H) andJ_(H) genes, and mouse light chain genes have been reported, but theyexhibit a limited diversity (and thus a limited usefulness) due in partto mispairing potential between human V_(H) and mouse V_(L) domains(see, e.g., Mageed et al., 2001, Rearrangement of the human heavy chainvariable region gene V3-23 in transgenic mice generates antibodiesreactive with a range of antigens on the basis of V_(H)CDR3 and residuesintrinsic to the heavy chain variable region, Clin. Exp. Immunol.123:1-5). Similarly, mice that bear two V_(H) genes (3-23 and 6-1) alongwith human D_(H) and J_(H) genes in a transgene containing the human μconstant gene (Bruggemann et al., 1991, Human antibody production intransgenic mice: expression from 100 kb of the human IgH locus, Eur. J.Immmunol. 21:1323-1326) and express them in human IgM chains with mouselight chains may exhibit a repertoire limited by mispairing(Mackworth-Young et al., 2003, The role of antigen in the selection ofthe human V3-23 immunoglobulin heavy chain variable region gene, Clin.Exp. Immunol. 134:420-425).

Other transgenic mice that express V_(H)-restricted fully human heavychains from a human transgene randomly inserted in the genome, with alimited human λ repertoire expressed from a fully human randomlyinserted transgene, have also been reported (see, e.g., Taylor et al.,1992, A transgenic mouse that expresses a diversity of human sequenceheavy and light chain immunoglobulins, Nucleic Acids Res.20(23):6287-6295; Wagner et al., 1994, Antibodies generated form humanimmunoglobulin miniloci in transgenic mice, Nucleic Acids Res.22(8):1389-1393). However, transgenic mice that express fully humanantibodies from transgenes randomly integrated into the mouse genome,and that comprise damaged endogenous loci, are known to exhibitsubstantial differences in immune response as compared with wild-typemice that affect the diversity of the antibody variable domainsobtainable from such mice.

Useful non-human animals that generate a diverse population of B cellsthat express human antibody variable domains from a restricted V_(H)gene repertoire and one or more D genes and one or more J genes will becapable of generating, preferably in some embodiments, repertoires ofrearranged variable region genes that will be sufficiently diverse. Invarious embodiments, diversity includes junctional diversity, somatichypermutation, and polymorphic diversity in V_(H) gene sequence (forembodiments where V_(H) genes are present in polymorphic forms).Combinatorial diversity occurs in the pairing of the V_(H) gene with oneof a plurality of cognate human light chain variable domains (which, invarious embodiments, comprise junctional diversity and/or somatichypermutations).

Non-human animals comprising a restricted human V_(H) gene repertoireand a complete or substantially complete human V_(L) gene repertoirewill in various embodiments generate populations of B cells that reflectthe various sources of diversity, such as junctional diversity (e.g.,VDJ, VJ joining, P additions, N additions), combinatorial diversity(e.g., cognate V_(H)-restricted human heavy, human light), and somatichypermutations. In embodiments comprising a restriction of the V_(H)repertoire to one human V_(H) gene, the one human V_(H) gene can bepresent in two or more variants. In various embodiments, the presence oftwo or more polymorphic forms of a V_(H) gene will enrich the diversityof the variable domains of the B cell population.

Variations in the germline sequences of gene segments (e.g., V genes)contribute to the diversity of the antibody response in humans. Therelative contribution to diversity due to V gene sequence differencesvaries among V genes. The degree of polymorphism varies across genefamilies, and is reflected in a plurality of haplotypes (stretches ofsequence with coinherited polymorphisms) capable of generating furtherdiversity as observed in V_(H) haplotype differences between related andunrelated individuals in the human population (see, e.g., Souroujon etal., 1989, Polymorphisms in Human H Chain V Region Genes from theV_(H)III Gene Family, J. Immunol. 143(2):706-711). Some have suggested,based on data from particularly polymorphic human V_(H) gene families,that haplotype diversity in the germline is a major contributor to V_(H)gene heterogeneity in the human population, which is reflected in thelarge diversity of different germline V_(H) genes across the humanpopulation (see, Sasso et al., 1990, Prevalence and Polymorphism ofHuman V_(H)3 Genes, J. Immunol. 145(8):2751-2757).

Although the human population displays a large diversity of haplotypeswith respect to the V_(H) gene repertoire due to widespreadpolymorphism, certain polymorphisms are reflected in prevalent (i.e.,conserved) alleles observed in the human population (Sasso et al.,1990). V_(H) polymorphism can be described in two principle forms. Thefirst is variation arising from allelic variation associated withdifferences among the nucleotide sequence between alleles of the samegene segment. The second arises from the numerous duplications,insertions, and/or deletions that have occurred at the immunoglobulinheavy chain locus. This has resulted in the unique situation in whichV_(H) genes derived by duplication from identical genes differ fromtheir respective alleles by one or more nucleotide substitutions. Thisalso directly influences the copy number of V_(H) genes at the heavychain locus.

Polymorphic alleles of the human immunoglobulin heavy chain variablegene segments (V_(H) genes) have largely been the result ofinsertion/deletion of gene segments and single nucleotide differenceswithin coding regions, both of which have the potential to havefunctional consequences on the immunoglobulin molecule. Table 1 setsforth the functional V_(H) genes listed by human V_(H) gene family andthe number of identified alleles for each V_(H) gene in the humanimmunoglobulin heavy chain locus. There are some findings to suggestthat polymorphic V_(H) genes have been implicated in susceptibility tocertain diseases such as, for example, rheumatoid arthritis, whereas inother cases a linkage between V_(H) and disease has been less clear.This ambiguity has been attributed to the copy number and presence ofvarious alleles in different human populations. In fact, several humanV_(H) genes demonstrate copy number variation (e.g., V_(H)1-2,V_(H)1-69, V_(H)2-26, V_(H)2-70, and V_(H)3-23). In various embodiments,humanized mice as described herein with restricted V_(H) repertoirescomprise multiple polymorphic variants of an individual V_(H) familymember (e.g., two or more polymorphic variants of V_(H)1-2, V_(H)1-69,V_(H)2-26, V_(H)2-70, or V_(H)3-23, replacing all or substantially allfunctional mouse V_(H) segments at an endogenous mouse locus). In aspecific embodiment, the two or more polymorphic variants of micedescribed herein are in number up to and including the number indicatedfor the corresponding V_(H) family member in Table 1 (e.g., forV_(H)1-69, 13 variants; for V_(H)1-2, five variants; etc.).

Commonly observed variants of particular human V_(H) genes are known inthe art. For example, one of the most complex polymorphisms in the V_(H)locus belongs to the V_(H)1-69 gene. The human V_(H)1-69 gene has 13reported alleles (Sasso et al., 1993, A fetally expressed immunoglobulinV_(H)1 gene belongs to a complex set of alleles, Journal of ClinicalInvestigation 91:2358-2367; Sasso et al., 1996, Expression of theimmunoglobulin V_(H) gene 51p1 is proportional to its germline gene copynumber, Journal of Clinical Investigation 97(9):2074-2080) and exists inat least three haplotypes that carry duplications of the V_(H)1-69 gene,which results in multiple copies of the V_(H) gene at a given locus.These polymorphic alleles include differences in the complementaritydetermining regions (CDRs), which may dramatically influence antigenspecificity. Table 2 sets for the reported alleles for human V_(H)1-69and human V_(H)1-2 genes and the SEQ ID NOs for the DNA and proteinsequences of the mature heavy chain variable regions.

Representative genomic DNA and full-length protein sequences of aV_(H)1-69 gene are set forth in SEQ ID NO: 4 and SEQ ID NO: 5,respectively. FIG. 5 and FIG. 6 set forth DNA and protein alignments ofthirteen reported V_(H)1-69 alleles, respectively. Representative DNAand protein sequences of a V_(H)1-2 gene are set forth in SEQ ID NO: 63and SEQ ID NO: 64, respectively. FIG. 8 and FIG. 9 set forth DNA andprotein alignments of five reported V_(H)1-2 alleles, respectively. FIG.7 and FIG. 10 set forth a percent identity/similarity matrix for alignedprotein sequences corresponding to thirteen-reported human V_(H)1-69 andfive reported human V_(H)1-2 alleles, respectively. In variousembodiments, the modified locus of the invention comprises a V_(H) geneselected from Table 1, present in two or more copy number, wherein thecopy number includes up to and including the number of alleles shown inTable 1. In one embodiment, the modified locus of the inventioncomprises a V_(H)1-69 or V_(H)1-2 gene selected from Table 2, present intwo or more copy number, wherein the copy number includes up to andincluding the number of alleles shown in Table 1.

TABLE 1 V_(H) Family V_(H) Gene Alleles V_(H) 1-2  5 Family 1 1-3  21-8  2 1-18 3 1-24 1 1-45 3 1-46 3 1-58 2 1-69 13 V_(H) 2-5  10 Family 22-26 1 2-70 13 V_(H) 3-7  3 Family 3 3-9  2 3-11 4 3-13 4 3-15 8 3-16 23-20 1 3-21 4 3-23 5 3-30 19 3-30-3 2 3-30-5 1 3-33 6 3-35 1 3-38 2 3-432 3-48 4 3-49 5 3-53 4 3-64 5 3-66 4 3-72 2 3-73 2 3-74 3 V_(H) 4-4  7Family 4 4-28 6 4-30-1 1 4-30-2 5 4-30-4 6 4-31 10 4-34 13 4-39 7 4-5910 4-61 8 V_(H) 5-51 5 Family 5 V_(H) 6-1  2 Family 6 V_(H) 7-4-1 5Family 7 7-81 1

TABLE 2 Accession SEQ ID NO: number (DNA/Protein) IgHV1-69 AlleleIgHV1-69*01 L22582 37/38 IgHV1-69*02 Z27506 39/40 IgHV1-69*03 X9234041/42 IgHV1-69*04 M83132 43/44 IgHV1-69*05 X67905 45/46 IgHV1-69*06L22583 47/48 IgHV1-69*07 Z29978 49/50 IgHV1-69*08 Z14309 51/52IgHV1-69*09 Z14307 53/54 IgHV1-69*10 Z14300 55/56 IgHV1-69*11 Z1429657/58 IgHV1-69*12 Z14301 59/60 IgHV1-69*13 Z14214 61/62 IgHV1-2 AlleleIgHV1-2*01 X07448 63/64 IgHV1-2*02 X62106 65/66 IgHV1-2*03 X92208 67/68IgHV1-2*04 Z12310 69/70 IgHV1-2*05 HM855674 71/72Antigen-Dependent Heavy Chain Variable Gene Usage

Antigen-dependent preferential usage of V_(H) genes can be exploited inthe development of human therapeutics targeting clinically significantantigens. The ability to generate a repertoire of antibody variabledomains using a particular V_(H) gene can provide a significantadvantage in the search for high-affinity antibody variable domains touse in human therapeutics. Studies on naive mouse and human V_(H) geneusage in antibody variable domains reveal that most heavy chain variabledomains are not derived from any particularly single or dominantly usedV_(H) gene. On the other hand, studies of antibody response to certainantigens reveal that in some cases a particular antibody responsedisplays a biased usage of a particular V_(H) gene in the B cellrepertoire following immunization.

Although the human V_(H) repertoire is quite diverse, by some estimatesthe expected frequency of usage of any given V_(H) gene, assuming randomselection of V_(H) genes, is about 2% (Brezinschek et al., 1995,Analysis of the Heavy Chain Repertoire of Human Peripheral B Cells UsingSingle-Cell Polymerase Chain Reaction, J. Immunol. 155:190-202). ButV_(H) usage in peripheral B cells in humans is skewed. In one study,functional V gene abundance followed the patternV_(H)3>V_(H)4>V_(H)1>V_(H)2>V_(H)5>V_(H)6 (Davidkova et al., 1997,Selective Usage of V_(H) Genes in Adult Human Lymphocyte Repertoires,Scand. J. Immunol. 45:62-73). One early study estimated that V_(H)3family usage frequency was about 0.65, whereas V_(H)1 family usagefrequency was about 0.15; these and other observations suggest that thegermline complexity of the human V_(H) repertoire is not preciselyreflected in the peripheral B cell compartment in humans that have anormal germline V_(H) repertoire, a situation that is similar to thatobserved in the mouse—i.e., V_(H) gene expression is non-stochastic(Zouali and These, 1991, Probing V_(H) Gene-Family Utilization in HumanPeripheral B Cells by In Situ Hybridization, J. Immunol.146(8):2855-2864). According to one report, V_(H) gene usage in humans,from greatest to least, is V_(H)3>V_(H)4>V_(H)1>V_(H)5>V_(H)2>V_(H)6;rearrangements in peripheral B cells reveal that V_(H)3 family usage ishigher than to be expected based on the relative number of germlineV_(H)3 genes (Brezinschek et al., 1995). According to another reportV_(H) usage in humans follows the patternV_(H)3>V_(H)5>V_(H)2>V_(H)1>V_(H)4>V_(H)6, based on analysis of pokeweedmitogen-activated peripheral small immunocompetent B cells (Davidkova etal., 1997, Selective Usage of V_(H) Genes in Adult Human B LymphocyteRepertoires, Scand. J. Immunol. 45:62-73). One report asserts that amongthe most frequently used V_(H)3 family members are 3-23, 3-30 and 3-54(Brezinschek et al., 1995). In the V_(H)4 family, member 4-59 and 4-4bwere found relatively more frequently (Id.), as well as 4-39 and 4-34(Brezinscheck et al., 1997, Analysis of the Human V_(H) Gene Repertoire,J. Clin. Invest. 99(10):2488-2501). Others postulate that the activatedheavy chain repertoire is skewed in favor of high V_(H)5 expression andlower V_(H)3 expression (Van Dijk-Hard and Lundkvist, 2002, Long-termkinetics of adult human antibody repertoires, Immunology 107:136-144).Other studies assert that the most commonly used V_(H) gene in the adulthuman repertoire is V_(H)4-59, followed by V_(H)3-23 and V_(H)3-48(Arnaout et al., 2001, High-Resolution Description of AntibodyHeavy-Chain Repertoires in Humans, PLoS ONE 6(8):108). Although usagestudies are based on relatively small sample numbers and thus exhibithigh variance, taken together the studies suggest that V gene expressionis not purely stochastic. Indeed, studies with particular antigens haveestablished that—in certain cases—the deck is firmly stacked againstcertain usages and in favor of others.

Over time, it became apparent that the observed repertoire of humanheavy chain variable domains generated in response to certain antigensis highly restricted. Some antigens are associated almost exclusivelywith neutralizing antibodies having only certain particular V_(H) genes,in the sense that effective neutralizing antibodies are derived fromessentially only one V_(H) gene. Such is the case for a number ofclinically important human pathogens.

V_(H)1-69-derived heavy chains have been observed in a variety ofantigen-specific antibody repertoires of therapeutic significance. Forinstance, V_(H)1-69 was frequently observed in heavy chain transcriptsof an IgE repertoire of peripheral blood lymphocytes in young childrenwith atopic disease (Bando et al., 2004, Characterization of V_(H)ε geneexpressed in PBL from children with atopic diseases: detection ofhomologous V_(H)1-69 derived transcripts from three unrelated patients,Immunology Letters 94:99-106). V_(H)1-69-derived heavy chains with ahigh degree of somatic hypermutation also occur in B cell lymphomas(Perez et al., 2009, Primary cutaneous B-cell lymphoma is associatedwith somatically hypermutated immunoglobulin variable genes and frequentuse of V_(H)1-69 and V_(H)4-59 segments, British Journal of Dermatology162:611-618), whereas some V_(H)1-69-derived heavy chains withessentially germline sequences (i.e., little to no somatichypermutation) have been observed among autoantibodies in patients withblood disorders (Pos et al., 2008, V_(H)1-69 germline encoded antibodiesdirected towards ADAMTS13 in patients with acquired thromboticthrombocytopenic purpura, Journal of Thrombosis and Haemostasis7:421-428).

Further, neutralizing antibodies against viral antigens such as HIV,influenza and hepatitis C (HCV) have been found to utilize germlineand/or somatically mutated V_(H)1-69-derived sequences (Miklos et al.,2000, Salivary gland mucosa-associated lymphoid tissue lymphomaimmunoglobulin V_(H) genes show frequent use of V1-69 with distinctiveCDR3 features, Blood 95(12):3878-3884; Kunert et al., 2004,Characterization of molecular features, antigen-binding, and in vitroproperties of IgG and IgM variants of 4E10, an anti-HIV type Ineutralizing monoclonal antibody, Aids Research and Human Retroviruses20(7):755-762; Chan et al., 2001, V_(H)1-69 gene is preferentially usedby hepatitis C virus-associated B cell lymphomas and by normal B cellsresponding to the E2 viral antigen, Blood 97(4):1023-1026; Carbonari etal., 2005, Hepatitis C virus drives the unconstrained monoclonalexpansion of V_(H)1-69-expressing memory B cells in type IIcryoglobulinemia: A model of infection-driven lymphomagenesis, Journalof Immunology 174:6532-6539; Wang and Palese, 2009, Universal epitopesof influenza virus hemagglutinins?, Nature Structural & MolecularBiology 16(3):233-234; Sui et al., 2009, Structural and functional basesfor broad-spectrum neutralization of avian and human influenza Aviruses, Nature Structural & Molecular Biology 16(3):265-273; Marasca etal., 2001, Immunoglobulin Gene Mutations and Frequent Use of V_(H)1-69and V_(H)4-34 Segments in Hepatitis C Virus-Positive and Hepatitis CVirus-Negative Nodal Marginal Zone B-Cell Lymphoma, Am. J. Pathol.159(1):253-261).

V_(H) usage bias is also observed in the humoral immune response toHaemophilus influenzae type b (Hib PS) in humans. Studies suggest thatthe V_(H)III family (the V_(H)IIIb subfamily in particular, V_(H)9.1)exclusively characterizes the human humoral response to Hib PS, withdiverse D and J genes (Adderson et al., 1991, Restricted Ig H Chain VGene Usage in the Human Antibody Response to Haemophilus influenzae Typeb Capsular Polysaccharide, J. Immunol. 147(5):1667-1674; Adderson etal., 1993, Restricted Immunoglobulin V_(H) Usage and VDJ Combinations inthe Human Response to Haemophilus influenzae Type b CapsularPolysaccharide, J. Clin. Invest. 91:2734-2743). Human J_(H) genes alsodisplay biased usage; J_(H)4 and J_(H)6 are observed at about 38-41% inperipheral B cells in humans (Brezinschek et al., 1995).

V_(H) usage in HIV-1-infected humans is biased against V_(H)3 usage andin favor of V_(H)1 and V_(H)4 gene families (Wisnewski et al., 1996,Human Antibody Variable Region Gene Usage in HIV-1 Infection, J.Acquired Immune Deficiency Syndromes & Human Retroviology 11(1):31-38).However, cDNA analysis of bone marrow from affected patients revealedsignificant V_(H)3 usage not expressed in the functional B cellrepertoire, where Fabs reflecting the V_(H)3 usage exhibited effectivein vitro neutralization of HIV-1 (Id.). It might be postulated that thehumoral immune response to HIV-1 infection is possibly attenuated due tothe V_(H) restriction; modified non-human animals as described herein(not infectable by HIV-1) might thus be useful for generatingneutralizing antibody domains derived from particular V_(H) genespresent in the genetically modified animals described herein, butderived from different V_(H) genes than those observed in the restrictedrepertoire of affected humans.

Thus, the ability to generate high affinity human antibody variabledomains in V_(H)-restricted mice, e.g., (restricted, e.g., to a V_(H)3family member and polymorph(s) thereof) immunized with HIV-1 mightprovide a rich resource for designing effective HIV-1-neutralizing humantherapeutics by thoroughly mining the restricted (e.g., restricted to aV_(H)3 family member or variant(s) thereof) repertoire of such animmunized mouse.

Restriction of the human antibody response to certain pathogens mayreduce the likelihood of obtaining antibody variable regions fromaffected humans that can serve as springboards for designing highaffinity neutralizing antibodies against the pathogen. For example, thehuman immune response to HIV-1 infection is clonally restrictedthroughout HIV-1 infection and into AIDS progression (Muller et al.,1993, B-cell abnormalities in AIDS: stable and clonally restrictedantibody response in HIV-1 infection, Scand. J. Immunol. 38:327-334;Wisnewski et al., 1996). Further, V_(H) genes are in general not presentin all polymorphic forms in individuals; certain individuals in certainpopulations possess one variant, whereas individuals in otherpopulations possess a different variant. Thus, the availability of abiological system that is restricted to a single V_(H) gene and itsvariants will in various embodiments provide a hitherto unexploitedsource of diversity for generating antibody variable regions (e.g.,human heavy and light cognate domains) based on a restricted V_(H) gene.

Genetically modified mice that express human heavy chain variableregions with restricted V_(H) gene segment usage are useful to generatea relatively large repertoire of junctionally diverse, combinatoriallydiverse, and somatically mutated high affinity human immunoglobulinheavy chain variable regions from an otherwise restricted repertoire. Arestricted repertoire, in this instance, refers to a predeterminedlimitation in germline genes that results in the mouse being unable toform a rearranged heavy chain gene that is derived from any V gene otherthan a preselected V gene. In embodiments that employ a preselected Vgene but not a preselected D and/or J gene, the repertoire is restrictedwith respect to the identity of the V gene but not the D and/or J gene.The identity of the preselected V gene (and any preselected D and/or Jgenes) is not limited to any particular V gene.

Designing a mouse so that it rearranges a single V_(H) gene (present asa single segment or a set of variants) with a variety of human D and Jgene segments (e.g., D_(H) and J_(H) segments) provides an in vivojunctional diversity/combinatorial diversity/somatic hypermutationpermutation machine that can be used to iterate mutations in resultingrearranged heavy chain variable region sequences (e.g., V/D/J or V/J, asthe case may be). In such a mouse, the clonal selection process operatesto select suitable variable regions that bind an antigen of interestthat are based on a single preselected V_(H) gene (or variants thereof).Because the mouse's clonal selection components are dedicated toselection based on the single preselected V_(H) gene segment, backgroundnoise is largely eradicated. With judicious selection of the V_(H) genesegment, a relatively larger number of clonally selected,antigen-specific antibodies can be screened in a shorter period of timethan with a mouse with a large diversity of V segments.

Preselecting and restricting a mouse to a single V segment provides asystem for permuting V/D/J junctions at a rate that is in variousembodiments higher than that observed in mice that otherwise have up to40 or more V segments to recombine with D and J regions. Removal ofother V segments frees the locus to form more V/D/J combinations for thepreselected V segment than otherwise observed. The increased number oftranscripts that result from the recombination of the preselected V withone of a plurality of D and one of a plurality of J segments will feedthose transcripts into the clonal selection system in the form of pre-Bcells, and the clonal selection system is thus dedicated to cycling Bcells that express the preselected V region. In this way, more unique Vregions derived from the preselected V segment can be screened by theorganism than would otherwise be possible in a given amount of time.

In various aspects, mice are described that enhance the junctionaldiversity of V/D recombinations for the preselected V region, becauseall or substantially all recombinations of the immunoglobulin heavychain variable locus will be of the preselected V segment and the D andJ segments that are placed in such mice. Therefore, the mice provide amethod for generating a diversity of CDR3 segments using a base, orrestricted V_(H) gene repertoire.

Genomic Location and Function of Mouse ADAM6

Male mice that lack the ability to express any functional ADAM6 proteinsurprisingly exhibit a defect in the ability of the mice to mate and togenerate offspring. The mice lack the ability to express a functionalADAM6 protein by virtue of a replacement of all or substantially allmouse immunoglobulin variable region gene segments with human variableregion gene segments. The loss of ADAM6 function results because theADAM6 locus is located within a region of the endogenous mouseimmunoglobulin heavy chain variable region gene locus, proximal to the3′ end of the V_(H) gene segment locus that is upstream of the D_(H)gene segments. In order to breed mice that are homozygous for areplacement of all or substantially all endogenous mouse heavy chainvariable sequences with a restricted human heavy chain sequence, it isgenerally a cumbersome approach to set up males and females that areeach homozygous for the restricted human heavy chain sequence and awaita productive mating. Successful litters are low in frequency and size.Instead, males heterozygous for the restricted human heavy chainsequence have been employed to mate with females homozygous for thereplacement to generate progeny that are heterozygous for the restrictedhuman heavy chain sequence, then a homozygous mouse is bred therefrom.The inventors have determined that the likely cause of the loss infertility in the male mice is the absence in homozygous male mice of afunctional ADAM6 protein.

In various aspects, male mice that comprise a damaged (i.e.,nonfunctional or marginally functional) ADAM6 gene exhibit a reductionor elimination of fertility. Because in mice (and other rodents) theADAM6 gene is located in the immunoglobulin heavy chain locus, theinventors have determined that in order to propagate mice, or create andmaintain a strain of mice, that comprise a humanized immunoglobulinheavy chain locus, various modified breeding or propagation schemes areemployed. The low fertility, or infertility, of male mice homozygous fora humanized immunoglobulin heavy chain variable gene locus rendersmaintaining such a modification in a mouse strain difficult. In variousembodiments, maintaining the strain comprises avoiding infertilityproblems exhibited by male mice homozygous for the humanized heavy chainlocus.

In one aspect, a method for maintaining a strain of mouse as describedherein is provided. The strain of mouse need not comprise an ectopicADAM6 sequence, and in various embodiments the strain of mouse ishomozygous or heterozygous for a knockout (e.g., a functional knockout)of ADAMS.

The mouse strain comprises a modification of an endogenousimmunoglobulin heavy chain locus that results in a reduction or loss infertility in a male mouse. In one embodiment, the modification comprisesa deletion of a regulatory region and/or a coding region of an ADAM6gene. In a specific embodiment, the modification comprises amodification of an endogenous ADAM6 gene (regulatory and/or codingregion) that reduces or eliminates fertility of a male mouse thatcomprises the modification; in a specific embodiment, the modificationreduces or eliminates fertility of a male mouse that is homozygous forthe modification.

In one embodiment, the mouse strain is homozygous or heterozygous for aknockout (e.g., a functional knockout) or a deletion of an ADAM6 gene.

In one embodiment, the mouse strain is maintained by isolating from amouse that is homozygous or heterozygous for the modification a cell,and employing the donor cell in host embryo, and gestating the hostembryo and donor cell in a surrogate mother, and obtaining from thesurrogate mother a progeny that comprises the genetic modification. Inone embodiment, the donor cell is an ES cell. In one embodiment, thedonor cell is a pluripotent cell, e.g., an induced pluripotent cell.

In one embodiment, the mouse strain is maintained by isolating from amouse that is homozygous or heterozygous for the modification a nucleicacid sequence comprising the modification, and introducing the nucleicacid sequence into a host nucleus, and gestating a cell comprising thenucleic acid sequence and the host nucleus in a suitable animal. In oneembodiment, the nucleic acid sequence is introduced into a host oocyteembryo.

In one embodiment, the mouse strain is maintained by isolating from amouse that is homozygous or heterozygous for the modification a nucleus,and introducing the nucleus into a host cell, and gestating the nucleusand host cell in a suitable animal to obtain a progeny that ishomozygous or heterozygous for the modification.

In one embodiment, the mouse strain is maintained by employing in vitrofertilization (IVF) of a female mouse (wild-type, homozygous for themodification, or heterozygous for the modification) employing a spermfrom a male mouse comprising the genetic modification. In oneembodiment, the male mouse is heterozygous for the genetic modification.In one embodiment, the male mouse is homozygous for the geneticmodification.

In one embodiment, the mouse strain is maintained by breeding a malemouse that is heterozygous for the genetic modification with a femalemouse to obtain progeny that comprises the genetic modification,identifying a male and a female progeny comprising the geneticmodification, and employing a male that is heterozygous for the geneticmodification in a breeding with a female that is wild-type, homozygous,or heterozygous for the genetic modification to obtain progenycomprising the genetic modification. In one embodiment, the step ofbreeding a male heterozygous for the genetic modification with awild-type female, a female heterozygous for the genetic modification, ora female homozygous for the genetic modification is repeated in order tomaintain the genetic modification in the mouse strain.

In one aspect, a method is provided for maintaining a mouse strain thatcomprises a replacement of an endogenous immunoglobulin heavy chainvariable gene locus with one or more human immunoglobulin heavy chainsequences, comprising breeding the mouse strain so as to generateheterozygous male mice, wherein the heterozygous male mice are bred tomaintain the genetic modification in the strain. In a specificembodiment, the strain is not maintained by any breeding of a homozygousmale with a wild-type female, or a female homozygous or heterozygous forthe genetic modification.

The ADAM6 protein is a member of the A Disintegrin And Metalloprotease(ADAM) family of proteins, which is a large family of proteins havingdiverse functions including cell adhesion. Some members of the ADAMfamily are implicated in spermatogenesis and fertilization. For example,ADAM2 encodes a subunit of the protein fertilin, which is implicated insperm-egg interactions. ADAM3, or cyritestin, appears necessary forsperm binding to the zona pellucida. The absence of either ADAM2 orADAM3 results in infertility. It has been postulated that ADAM2, ADAM3,and ADAM6 form a complex on the surface of mouse sperm cells. The humancounterpart gene (human ADAM6), normally found between human V_(H) genesegments V_(H)1-2 and V_(H)6-1 in the human immunoglobulin heavy chainlocus, appears to be a pseudogene. In mice, there are two ADAM6genes—ADAM6a and ADAM6b—that are found in an intergenic region betweenmouse V_(H) and D_(H) gene segments, and in the mouse the ADAM6a andADAM6b genes are oriented in opposite transcriptional orientation tothat of the surrounding immunoglobulin gene segments. In mice, afunctional ADAM6 locus is apparently required for normal fertilization.A functional ADAM6 locus or sequence, then, refers to an ADAM6 locus orsequence that can complement, or rescue, the drastically reducedfertilization exhibited in male mice with missing or nonfunctionalendogenous ADAM6 loci.

The position of the intergenic sequence in mice that encodes ADAM6a andADAM6b renders the intergenic sequence susceptible to modification whenmodifying an endogenous mouse heavy chain. When V_(H) gene segments aredeleted or replaced, or when D_(H) gene segments are deleted orreplaced, there is a high probability that a resulting mouse willexhibit a severe deficit in fertility. In order to compensate for thedeficit, the mouse is modified to include a nucleotide sequence thatencodes a protein that will complement the loss in ADAM6 activity due toa modification of the endogenous mouse ADAM6 locus. In variousembodiments, the complementing nucleotide sequence is one that encodes amouse ADAM6a, a mouse ADAM6b, or a homolog or ortholog or functionalfragment thereof that rescues the fertility deficit. Alternatively,suitable methods to preserve the endogenous ADAM6 locus can be employed,while rendering the endogenous immunoglobulin heavy chain sequencesflanking the mouse ADAM6 locus incapable of rearranging to encode afunctional endogenous heavy chain variable region. Exemplary alternativemethods include manipulation of large portions of mouse chromosomes thatposition the endogenous immunoglobulin heavy chain variable region lociin such a way that they are incapable of rearranging to encode afunctional heavy chain variable region that is operably linked to anendogenous heavy chain constant gene. In various embodiments, themethods include inversions and/or translocations of mouse chromosomalfragments containing endogenous immunoglobulin heavy chain genesegments.

The nucleotide sequence that rescues fertility can be placed at anysuitable position. It can be placed in the intergenic region, or in anysuitable position in the genome (i.e., ectopically). In one embodiment,the nucleotide sequence can be introduced into a transgene that randomlyintegrates into the mouse genome. In one embodiment, the sequence can bemaintained episomally, that is, on a separate nucleic acid rather thanon a mouse chromosome. Suitable positions include positions that aretranscriptionally permissive or active, e.g., a ROSA26 locus (Zambrowiczet al., 1997, PNAS USA 94:3789-3794), a BT-5 locus (Michael et al.,1999, Mech. Dev. 85:35-47), or an Oct4 locus (Wallace et al., 2000,Nucleic Acids Res. 28:1455-1464). Targeting nucleotide sequences totranscriptionally active loci are described, e.g., in U.S. Pat. No.7,473,557, herein incorporated by reference.

Alternatively, the nucleotide sequence that rescues fertility can becoupled with an inducible promoter so as to facilitate optimalexpression in the appropriate cells and/or tissues, e.g., reproductivetissues. Exemplary inducible promoters include promoters activated byphysical (e.g., heat shock promoter) and/or chemical means (e.g., IPTGor Tetracycline).

Further, expression of the nucleotide sequence can be linked to othergenes so as to achieve expression at specific stages of development orwithin specific tissues. Such expression can be achieved by placing thenucleotide sequence in operable linkage with the promoter of a geneexpressed at a specific stage of development. For example,immunoglobulin sequences from one species engineered into the genome ofa host species are place in operable linkage with a promoter sequence ofa CD19 gene (a B cell specific gene) from the host species. Bcell-specific expression at precise developmental stages whenimmunoglobulins are expressed is achieved.

Yet another method to achieve robust expression of an insertednucleotide sequence is to employ a constitutive promoter. Exemplaryconstitutive promoters include SV40, CMV, UBC, EF1A, PGK and CAGG. In asimilar fashion, the desired nucleotide sequence is placed in operablelinkage with a selected constitutive promoter, which provides high levelof expression of the protein(s) encoded by the nucleotide sequence.

The term “ectopic” is intended to include a displacement, or a placementat a position that is not normally encountered in nature (e.g.,placement of a nucleic acid sequence at a position that is not the sameposition as the nucleic acid sequence is found in a wild-type mouse).The term, in various embodiments, is used in the sense of its objectbeing out of its normal, or proper, position. For example, the phrase“an ectopic nucleotide sequence encoding . . . ” refers to a nucleotidesequence that appears at a position at which it is not normallyencountered in the mouse. For example, in the case of an ectopicnucleotide sequence encoding a mouse ADAM6 protein (or an ortholog orhomolog or fragment thereof that provides the same or similar fertilitybenefit on male mice), the sequence can be placed at a differentposition in the mouse's genome than is normally found in a wild-typemouse. In such cases, novel sequence junctions of mouse sequence will becreated by placing the sequence at a different position in the mouse'sgenome than in a wild-type mouse. A functional homolog or ortholog ofmouse ADAM6 is a sequence that confers a rescue of fertility loss (e.g.,loss of the ability of a male mouse to generate offspring by mating)that is observed in an ADAM6^(−/−) mouse. Functional homologs ororthologs include proteins that have at least about 89% identity ormore, e.g., up to 99% identity, to the amino acid sequence of ADAM6aand/or to the amino acid sequence of ADAM6b, and that can complement, orrescue ability to successfully mate, of a mouse that has a genotype thatincludes a deletion or knockout of ADAM6a and/or ADAM6b.

The ectopic position can be anywhere (e.g., as with random insertion ofa transgene containing a mouse ADAM6 sequence), or can be, e.g., at aposition that approximates (but is not precisely the same as) itslocation in a wild-type mouse (e.g., in a modified endogenous mouseimmunoglobulin locus, but either upstream or downstream of its naturalposition, e.g., within a modified immunoglobulin locus but betweendifferent gene segments, or at a different position in a mouse V-Dintergenic sequence). One example of an ectopic placement is maintainingthe position normally found in wild-type mice within the endogenousimmunoglobulin heavy chain locus while rendering the surroundingendogenous heavy chain gene segments in capable of rearranging to encodea functional heavy chain containing an endogenous heavy chain constantregion. In this example, this may be accomplished by inversion of thechromosomal fragment containing the endogenous immunoglobulin heavychain variable loci, e.g. using engineered site-specific recombinationsites placed at positions flanking the variable region locus. Thus, uponrecombination the endogenous heavy chain variable region loci are placedat a great distance away from the endogenous heavy chain constant regiongenes thereby preventing rearrangement to encode a functional heavychain containing an endogenous heavy chain constant region. Otherexemplary methods to achieve functional silencing of the endogenousimmunoglobulin heavy chain variable gene locus while maintaining afunctional ADAM6 locus will apparent to persons of skill upon readingthis disclosure and/or in combination with methods known in the art.With such a placement of the endogenous heavy chain locus, theendogenous ADAM6 genes are maintained and the endogenous immunoglobulinheavy chain locus is functionally silenced.

Another example of an ectopic placement is placement within a humanizedimmunoglobulin heavy chain locus. For example, a mouse comprising areplacement of one or more endogenous V_(H) gene segments with a singlehuman V_(H) gene segment, wherein the replacement removes an endogenousADAM6 sequence, can be engineered to have a mouse ADAM6 sequence locatedwithin an intergenic sequence that lies between the single human V_(H)gene segment and a human D_(H) gene segment. Another example of anectopic placement is placement of the mouse ADAM6 sequence at a position5′ (with respect to the direction of transcription of the single humanV_(H) gene segment) to the human V_(H) gene segment. A position 5′ tothe single human V_(H) gene segment may be in close proximity, e.g., afew hundred base pairs to a few kb, or distant, e.g., several kb tohundreds of kb or even a megabase or greater, relative to the humanV_(H) gene segment. The resulting modification would generate a(ectopic) mouse ADAM6 sequence within or contiguous, or even on the samechromosome, with a human gene sequence, and the (ectopic) placement ofthe mouse ADAM6 sequence within the human gene sequence can approximatethe position of the mouse ADAM6 sequence (i.e., within the V-Dintergenic region). The resulting sequence junctions created by thejoining of a (ectopic) mouse ADAM6 sequence within or adjacent to ahuman gene sequence (e.g., an immunoglobulin gene sequence) within thegermline of the mouse would be novel as compared to the same or similarposition in the genome of a wild-type mouse.

In various embodiments, non-human animals are provided that lack anADAM6 or ortholog or homolog thereof, wherein the lack renders thenon-human animal infertile, or substantially reduces fertility of thenon-human animal. In various embodiments, the lack of ADAM6 or orthologor homolog thereof is due to a modification of an endogenousimmunoglobulin heavy chain locus. A substantial reduction in fertilityis, e.g., a reduction in fertility (e.g., breeding frequency, pups perlitter, litters per year, etc.) of about 50%, 60%, 70%, 80%, 90%, or 95%or more. In various embodiments, the non-human animals are supplementedwith a mouse ADAM6 gene or ortholog or homolog or functional fragmentthereof that is functional in a male of the non-human animal, whereinthe supplemented ADAM6 gene or ortholog or homolog or functionalfragment thereof rescues the reduction in fertility in whole or insubstantial part. A rescue of fertility in substantial part is, e.g., arestoration of fertility such that the non-human animal exhibits afertility that is at least 70%, 80%, or 90% or more as compared with anunmodified (i.e., an animal without a modification to the ADAM6 gene orortholog or homolog thereof) heavy chain locus.

The sequence that confers upon the genetically modified animal (i.e.,the animal that lacks a functional ADAM6 or ortholog or homolog thereof,due to, e.g., a modification of a immunoglobulin heavy chain locus) is,in various embodiments, selected from an ADAM6 gene or ortholog orhomolog thereof. For example, in a mouse, the loss of ADAM6 function isrescued by adding, in one embodiment, a mouse ADAM6 gene. In oneembodiment, the loss of ADAM6 function in the mouse is rescued by addingan ortholog or homolog of a closely related specie with respect to themouse, e.g., a rodent, e.g., a mouse of a different strain or species, arat of any species, a rodent; wherein the addition of the ortholog orhomolog to the mouse rescues the loss of fertility due to loss of ADAM6function or loss of an ADAM6 gene. Orthologs and homologs from otherspecies, in various embodiments, are selected from a phylogeneticallyrelated species and, in various embodiments, exhibit a percent identitywith the endogenous ADAM6 (or ortholog) that is about 80% or more, 85%or more, 90% or more, 95% or more, 96% or more, or 97% or more; and thatrescue ADAMS-related or (in a non-mouse) ADAM6 ortholog-related loss offertility. For example, in a genetically modified male rat that lacksADAM6 function (e.g., a rat with an endogenous immunoglobulin heavychain variable region replaced with a human immunoglobulin heavy chainvariable region, or a knockout in the rat immunoglobulin heavy chainregion), loss of fertility in the rat is rescued by addition of a ratADAM6 or, in some embodiments, an ortholog of a rat ADAM6 (e.g., anADAM6 ortholog from another rat strain or species, or, in oneembodiment, from a mouse).

Thus, in various embodiments, genetically modified animals that exhibitno fertility or a reduction in fertility due to modification of anucleic acid sequence encoding an ADAM6 protein (or ortholog or homologthereof) or a regulatory region operably linked with the nucleic acidsequence, comprise a nucleic acid sequence that complements, orrestores, the loss in fertility where the nucleic acid sequence thatcomplements or restores the loss in fertility is from a different strainof the same species or from a phylogenetically related species. Invarious embodiments, the complementing nucleic acid sequence is an ADAM6ortholog or homolog or functional fragment thereof. In variousembodiments, the complementing ADAM6 ortholog or homolog or functionalfragment thereof is from a non-human animal that is closely related tothe genetically modified animal having the fertility defect. Forexample, where the genetically modified animal is a mouse of aparticular strain, an ADAM6 ortholog or homolog or functional fragmentthereof can be obtained from a mouse of another strain, or a mouse of arelated species. In one embodiment, where the genetically modifiedanimal comprising the fertility defect is of the order Rodentia, theADAM6 ortholog or homolog or functional fragment thereof is from anotheranimal of the order Rodentia. In one embodiment, the geneticallymodified animal comprising the fertility defect is of a suborderMyomoropha (e.g., jerboas, jumping mice, mouse-like hamsters, hamsters,New World rats and mice, voles, true mice and rats, gerbils, spiny mice,crested rats, climbing mice, rock mice, white-tailed rats, malagasy ratsand mice, spiny dormice, mole rats, bamboo rats, zokors), and the ADAM6ortholog or homolog or functional fragment thereof is selected from ananimal of order Rodentia, or of the suborder Myomorpha.

In one embodiment, the genetically modified animal is from thesuperfamily Dipodoidea, and the ADAM6 ortholog or homolog or functionalfragment thereof is from the superfamily Muroidea. In one embodiment,the genetically modified animal is from the superfamily Muroidea, andthe ADAM6 ortholog or homolog or functional fragment thereof is from thesuperfamily Dipodoidea.

In one embodiment, the genetically modified animal is a rodent. In oneembodiment, the rodent is selected from the superfamily Muroidea, andthe ADAM6 ortholog or homolog is from a different species within thesuperfamily Muroidea. In one embodiment, the genetically modified animalis from a family selected from Calomyscidae (e.g., mouse-like hamsters),Cricetidae (e.g., hamster, New World rats and mice, voles), Muridae(true mice and rats, gerbils, spiny mice, crested rats), Nesomyidae(climbing mice, rock mice, with-tailed rats, Malagasy rats and mice),Platacanthomyidae (e.g., spiny dormice), and Spalacidae (e.g., molerates, bamboo rats, and zokors); and the ADAM6 ortholog or homolog isselected from a different species of the same family. In a specificembodiment, the genetically modified rodent is selected from a truemouse or rat (family Muridae), and the ADAM6 ortholog or homolog is froma species selected from a gerbil, spiny mouse, or crested rat. In oneembodiment, the genetically modified mouse is from a member of thefamily Muridae, and the ADAM6 ortholog or homolog is from a differentspecies of the family Muridae. In a specific embodiment, the geneticallymodified rodent is a mouse of the family Muridae, and the ADAM6 orthologor homolog is from a rat, gerbil, spiny mouse, or crested rat of thefamily Muridae.

In various embodiments, one or more rodent ADAM6 orthologs or homologsor functional fragments thereof of a rodent in a family restoresfertility to a genetically modified rodent of the same family that lacksan ADAM6 ortholog or homolog (e.g., Cricetidae (e.g., hamsters, NewWorld rats and mice, voles); Muridae (e.g., true mice and rats, gerbils,spiny mice, crested rats)).

In various embodiments, ADAM6 orthologs, homologs, and fragments thereofare assessed for functionality by ascertaining whether the ortholog,homolog, or fragment restores fertility to a genetically modified malenon-human animal that lacks ADAM6 activity (e.g., a rodent, e.g., amouse or rat, that comprises a knockout of ADAM6 or its ortholog). Invarious embodiments, functionality is defined as the ability of a spermof a genetically modified animal lacking an endogenous ADAM6 or orthologor homolog thereof to migrate an oviduct and fertilize an ovum of thesame specie of genetically modified animal.

In various aspects, mice that comprise deletions or replacements of theendogenous heavy chain variable region locus or portions thereof can bemade that contain an ectopic nucleotide sequence that encodes a proteinthat confers similar fertility benefits to mouse ADAM6 (e.g., anortholog or a homolog or a fragment thereof that is functional in a malemouse). The ectopic nucleotide sequence can include a nucleotidesequence that encodes a protein that is an ADAM6 homolog or ortholog (orfragment thereof) of a different mouse strain or a different species,e.g., a different rodent species, and that confers a benefit infertility, e.g., increased number of litters over a specified timeperiod, and/or increased number of pups per litter, and/or the abilityof a sperm cell of a male mouse to traverse through a mouse oviduct tofertilize a mouse egg.

In one embodiment, the ADAMS is a homolog or ortholog that is at least89% to 99% identical to a mouse ADAM6 protein (e.g., at least 89% to 99%identical to mouse ADAM6a or mouse ADAM6b). In one embodiment, theectopic nucleotide sequence encodes one or more proteins independentlyselected from a protein at least 89% identical to mouse ADAM6a, aprotein at least 89% identical to mouse ADAM6b, and a combinationthereof. In one embodiment, the homolog or ortholog is a rat, hamster,mouse, or guinea pig protein that is or is modified to be about 89% ormore identical to mouse ADAM6a and/or mouse ADAM6b. In one embodiment,the homolog or ortholog is or is at least 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, or 99% identical to a mouse ADAM6a and/or mouse ADAM6b.

Ectopic ADAM6 in Humanized Heavy Chain Mice

Developments in gene targeting, e.g., the development of bacterialartificial chromosomes (BACs), now enable the recombination ofrelatively large genomic fragments. BAC engineering has allowed for theability to make large deletions, and large insertions, into mouse EScells.

Mice that make human antibodies have been available for some time now.Although they represent an important advance in the development of humantherapeutic antibodies, these mice display a number of significantabnormalities that limit their usefulness. For example, they displaycompromised B cell development. The compromised development may be dueto a variety of differences between the transgenic mice and wild-typemice.

Human antibodies might not optimally interact with mouse pre B cell or Bcell receptors on the surface of mouse cells that signal for maturation,proliferation, or survival during clonal selection. Fully humanantibodies might not optimally interact with a mouse Fc receptor system;mice express Fc receptors that do not display a one-to-onecorrespondence with human Fc receptors. Finally, various mice that makefully human antibodies do not include all genuine mouse sequences, e.g.,downstream enhancer elements and other locus control elements, which maybe required for wild-type B cell development.

Mice that make fully human antibodies generally comprise endogenousimmunoglobulin loci that are disabled in some way, and human transgenesthat comprise variable and constant immunoglobulin gene segments areintroduced into a random location in the mouse genome. As long as theendogenous locus is sufficiently disabled so as not to rearrange genesegments to form a functional immunoglobulin gene, the goal of makingfully human antibodies in such a mouse can be achieved-albeit withcompromised B cell development.

Although compelled to make fully human antibodies from the humantransgene locus, generating human antibodies in a mouse is apparently anunfavored process. In some mice, the process is so unfavored as toresult in formation of chimeric human variable/mouse constant heavychains (but not light chains) through the mechanism of trans-switching.By this mechanism, transcripts that encode fully human antibodiesundergo isotype switching in trans from the human isotype to a mouseisotype. The process is in trans, because the fully human transgene islocated apart from the endogenous locus that retains an undamaged copyof a mouse heavy chain constant region gene. Although in such micetrans-switching is readily apparent the phenomenon is still insufficientto rescue B cell development, which remains frankly impaired. In anyevent, trans-switched antibodies made in such mice retain fully humanlight chains, since the phenomenon of trans-switching apparently doesnot occur with respect to light chains; trans-switching presumablyrelies on switch sequences in endogenous loci used (albeit differently)in normal isotype switching in cis. Thus, even when mice engineered tomake fully human antibodies select a trans-switching mechanism to makeantibodies with mouse constant regions, the strategy is stillinsufficient to rescue normal B cell development.

A primary concern in making antibody-based human therapeutics, e.g.,anti-pathogen antibodies, is identifying useful variable domains thatspecifically recognize particular epitopes and bind them with adesirable affinity, usually—but not always—with high affinity. Mice asdescribed herein, which contain a precise replacement of mouseimmunoglobulin heavy chain variable regions with a restricted number ofhuman immunoglobulin heavy chain variable gene segments at theendogenous mouse loci, display near wild-type B cell development and thevariable regions generated in response to immunization are fully human,wherein the heavy chains are derived from a single human V_(H) genesegment. Thus, such mice provide a platform to generate a panel of heavychain complementary determining regions (CDRs) that are specificallydirected to bind a given antigen, e.g., a pathogenic virus.

Mice as described herein contain a precise, large-scale replacement ofgermline variable gene loci of mouse immunoglobulin heavy chain (IgH)with a restricted human immunoglobulin heavy chain variable locus, andimmunoglobulin light chain (e.g., κ light chain, Igκ) with an equivalenthuman immunoglobulin κ light chain variable gene locus, at theendogenous loci. This precise replacement results in a mouse with hybridimmunoglobulin loci that make heavy and light chains that have a humanvariable regions and a mouse constant region. The precise replacement ofmouse V_(H)-D_(H)-J_(H) and Vκ-Jκ segments leave flanking mousesequences intact and functional at the hybrid immunoglobulin loci. Thehumoral immune system of the mouse functions like that of a wild-typemouse. B cell development is unhindered in any significant respect and asomatically mutated panel of human heavy chain CDRs is generated in themouse upon antigen challenge.

Mice as described herein are possible because immunoglobulin genesegments for heavy and κ light chains rearrange similarly in humans andmice, which is not to say that their loci are the same or even nearlyso—clearly they are not. However, the loci are similar enough thathumanization of the heavy chain variable gene locus can be accomplishedby replacing about three million base pairs of contiguous mouse sequencethat contains all the V_(H), D_(H), and J_(H) gene segments with acontiguous human genomic sequence containing a restricted human heavychain locus.

In some embodiments, further replacement of certain mouse constantregion gene sequences with human gene sequences (e.g., replacement ofmouse C_(H)1 sequence with human C_(H)1 sequence, and replacement ofmouse C_(L) sequence with human C_(L) sequence) results in mice withhybrid immunoglobulin loci that make antibodies that have human variableregions and partly human constant regions, suitable for, e.g., makingfully human antibody fragments, e.g., fully human Fab's. Mice withhybrid immunoglobulin loci exhibit normal variable gene segmentrearrangement, normal somatic hypermutation frequencies, and normalclass switching. These mice exhibit a humoral immune system that isindistinguishable from wild type mice, and display normal cellpopulations at all stages of B cell development and normal lymphoidorgan structures—even where the mice lack a full repertoire of humanvariable region gene segments. Immunizing these mice results in robusthumoral responses that display a wide diversity of heavy chain CDRs andlight chain variable gene segment usage.

The precise replacement of mouse germline variable region gene segmentsallows for making mice that have partly human immunoglobulin loci.Because the partly human immunoglobulin loci rearrange, hypermutate, andclass switch normally, the partly human immunoglobulin loci generateantibodies in a mouse that comprise human variable regions. Nucleotidesequences that encode the variable regions can be identified and cloned,then fused (e.g., in an in vitro system) with any sequences of choice,e.g., any immunoglobulin isotype suitable for a particular use,resulting in an antibody or antigen-binding protein derived wholly fromhuman sequences.

Large-scale humanization by recombineering methods were used to modifymouse embryonic stem (ES) cells to precisely replace up to threemegabases of the mouse heavy chain immunoglobulin locus that includedessentially all of the mouse V_(H), D_(H), and J_(H) gene segments witha human genomic sequence containing a restricted human heavy chain locusincluding a single human V_(H) gene segment, 27 human D_(H) genesegments, and six human J_(H) gene segments. Up to a one-half megabasesegment of the human genome comprising one of two repeats encodingessentially all human Vκ and Jκ gene segments was used to replace athree megabase segment of the mouse immunoglobulin κ light chain locuscontaining essentially all of the mouse Vκ and Jκ gene segments.

Mice with such replaced immunoglobulin loci can comprise a disruption ordeletion of the endogenous mouse ADAM6 locus, which is normally foundbetween the 3′-most V_(H) gene segment and the 5′-most D_(H) genesegment at the mouse immunoglobulin heavy chain locus. Disruption inthis region can lead to reduction or elimination of functionality of theendogenous mouse ADAM6 locus. If one, or both, of the 3′-most V_(H) genesegments of the human heavy chain repertoire are used in construction ofthe restricted human heavy chain locus, an intergenic region containinga pseudogene that appears to be a human ADAM6 pseudogene is presentbetween these V_(H) gene segments, i.e., between human V_(H)1-2 andV_(H)1-6. However, male mice that comprise this human intergenicsequence exhibit a reduction in fertility (see U.S. Ser. No. 13/404,075,herein incorporated by reference).

Mice are described that comprise the restricted human heavy chain andequivalent human κ light chain loci as described above, and that alsocomprise an ectopic nucleic acid sequence encoding a mouse ADAM6, wherethe mice exhibit essentially normal fertility. In one embodiment, theectopic nucleic acid sequence comprises a mouse ADAM6a and/or a mouseADAM6b sequence or functional fragments thereof placed between a humanV_(n)1-69 and a human D_(H)1-1 at a modified endogenous heavy chainlocus. In one embodiment, the ectopic nucleic acid sequence is SEQ IDNO: 77, placed between a human V_(H)1-69 and a human D_(H)1-1 at amodified endogenous heavy chain locus. The direction of transcription ofthe ADAM6 genes of SEQ ID NO: 77 are opposite with respect to thedirection of transcription of the surrounding human gene segments. Inone embodiment, the ectopic nucleic acid sequence comprises a mouseADAM6a and/or a mouse ADAM6b sequence or functional fragments thereofplaced upstream (or 5′) of a human V_(H)1-2 gene segment at a modifiedendogenous heavy chain locus. In one embodiment, the ectopic nucleicacid sequence is SEQ ID NO: 73, placed upstream (or 5′) of a humanV_(H)1-2 gene segment at a modified endogenous heavy chain locus. Thedirection of transcription of the ADAM6 genes of SEQ ID NO: 73 areopposite with respect to the direction of transcription of thesurrounding human gene segments (e.g. a human V_(H)1-2 gene segment).

Although examples herein show rescue of fertility by placing the ectopicsequence between the indicated human gene segments, skilled persons willrecognize that placement of the ectopic sequence at any suitabletranscriptionally-permissive locus in the mouse genome (or evenextrachromosomally) will be expected to similarly rescue fertility in amale mouse.

The phenomenon of complementing a mouse that lacks a functional ADAM6locus with an ectopic sequence that comprises a mouse ADAM6 gene orortholog or homolog or functional fragment thereof is a general methodthat is applicable to rescuing any mice with nonfunctional or minimallyfunctional endogenous ADAM6 loci. Thus, a great many mice that comprisean ADAM6-disrupting modification of the immunoglobulin heavy chain locuscan be rescued with the compositions and methods of the invention.Accordingly, the invention comprises mice with a wide variety ofmodifications of immunoglobulin heavy chain loci that compromiseendogenous ADAM6 function. Some (non-limiting) examples are provided inthis description. In addition to the mice described, the compositionsand methods related to ADAM6 can be used in a great many applications,e.g., when modifying a heavy chain locus in a wide variety of ways.

In one aspect, a mouse is provided that comprises an ectopic ADAM6sequence that encodes a functional ADAM6 protein (or ortholog or homologor functional fragment thereof), a replacement of all or substantiallyall mouse V_(H) gene segments with a single human V_(H) gene segments, areplacement of all or substantially all mouse D_(H) gene segments andJ_(H) gene segments with human D_(H) and human J_(H) gene segments;wherein the mouse lacks a C_(H)1 and/or hinge region. In one embodiment,the mouse makes a single variable domain binding protein that is a dimerof immunoglobulin chains selected from: (a) human V_(H)-mouseC_(H)1-mouse C_(H)2-mouse C_(H)3; (b) human V_(H)-mouse hinge-mouseC_(H)2-mouse C_(H)3; and, (c) human V_(H)-mouse C_(H)2-mouse C_(H)3.

In one aspect, the nucleotide sequence that rescues fertility is placedupstream (or 5′) of a human immunoglobulin heavy chain variable regionsequence (e.g., upstream of a human V_(H)1-2 or V_(H)1-69 gene segment)in a mouse that has a replacement of one or more mouse immunoglobulinheavy chain variable gene segments (mV_(H)'s, mD_(H)'S, and/or mJ_(H)'S)with one or more human immunoglobulin heavy chain variable gene segments(hV_(H)'s, hD_(H)'s, and/or hJ_(H)'s), and the mouse further comprises areplacement of one or more mouse immunoglobulin κ light chain variablegene segments (mVκ's and/or mJκ's) with one or more human immunoglobulinκ light chain variable gene segments (hVκ's and/or hJκ's).

In one aspect, the nucleotide sequence that rescues fertility is placedwithin a human immunoglobulin heavy chain variable region sequence(e.g., between human V_(H)1-69 or human V_(H)1-2 and a human D_(H)1-1gene segment) in a mouse that has a replacement of one or more mouseimmunoglobulin heavy chain variable gene segments (mV_(H)'s, mD_(H)'s,and/or mJ_(H)'s) with one or more human immunoglobulin heavy chainvariable gene segments (hV_(H)'s, hD_(H)'s, and/or hJ_(H)'s), and themouse further comprises a replacement of one or more mouseimmunoglobulin κ light chain variable gene segments (mVκ's and/or mJκ's)with one or more human immunoglobulin κ light chain variable genesegments (hVκ's and/or hJκ's).

In one embodiment, the one or more mouse immunoglobulin heavy chainvariable gene segments comprises about three megabases of the mouseimmunoglobulin heavy chain locus. In one embodiment, the one or moremouse immunoglobulin heavy chain variable gene segments comprises atleast 89 V_(H) gene segments, at least 13 D_(H) gene segments, at leastfour J_(H) gene segments or a combination thereof of the mouseimmunoglobulin heavy chain locus. In one embodiment, the one or morehuman immunoglobulin heavy chain variable gene segments comprises arestricted number of (e.g., one, two or three) V_(H) gene segments, atleast 27 D_(H) gene segments, at least six J_(H) gene segments or acombination thereof of a human immunoglobulin heavy chain locus. In aspecific embodiment, the restricted number of human V_(H) gene segmentsis one.

In one embodiment, the one or more mouse immunoglobulin κ light chainvariable gene segments comprises about three megabases of the mouseimmunoglobulin κ light chain locus. In one embodiment, the one or moremouse immunoglobulin κ light chain variable gene segments comprises atleast 137 Vκ gene segments, at least five Jκ gene segments or acombination thereof of the mouse immunoglobulin κ light chain locus. Inone embodiment, the one or more human immunoglobulin κ light chainvariable gene segments comprises about one-half megabase of a humanimmunoglobulin κ light chain locus. In a specific embodiment, the one ormore human immunoglobulin κ light chain variable gene segments comprisesthe proximal repeat (with respect to the immunoglobulin κ constantregion) of a human immunoglobulin κ light chain locus. In oneembodiment, the one or more human immunoglobulin κ light chain variablegene segments comprises at least 40Vκ gene segments, at least five Jκgene segments or a combination thereof of a human immunoglobulin κ lightchain locus.

In one embodiment, the nucleotide sequence is place between two humanimmunoglobulin gene segments. In a specific embodiment, the two humanimmunoglobulin gene segments are heavy chain gene segments. In oneembodiment, the nucleotide sequence is placed between a human V_(H)1-69gene segment and a human D_(H)1-1 gene segment. In one embodiment, thenucleotide sequence is placed between a human V_(H)12 gene segment and ahuman D_(H)1-1 gene segment. In one embodiment, the mouse so modifiedcomprises a replacement of mouse immunoglobulin heavy chain variablegene segments with a single human V_(H) gene segments, 27 human D_(H)gene segments and six human J_(H) gene segments, and a replacement ofmouse immunoglobulin κ light chain variable gene segments with at least40 human Vκ gene segments and five human Jκ gene segments.

In one aspect, a functional mouse ADAM6 locus (or ortholog or homolog orfunctional fragment thereof) is present in the midst of mouse genesegments that are present at the endogenous mouse heavy chain variableregion locus, said locus incapable of rearranging to encode a functionalheavy chain containing an endogenous heavy chain constant region. In oneembodiment, the endogenous mouse heavy chain locus comprises at leastone and up to 89 V_(H) gene segments, at least one and up to 13 D_(H)gene segments, at least one and up to four J_(H) gene segments and acombination thereof. In various embodiments, a functional mouse ADAM6locus (or ortholog or homolog or functional fragment thereof) encodesone or more ADAM6 proteins that are functional in the mouse, wherein theone or more ADAM6 proteins comprise SEQ ID NO: 1, SEQ ID NO: 2 and/or acombination thereof.

In one aspect, a functional mouse ADAM6 locus (or ortholog or homolog orfunctional fragment thereof) is present in the midst of human genesegments that replace endogenous mouse gene segments. In one embodiment,at least 89 mouse V_(H) gene segments are removed and replaced with one,two or three human V_(H) gene segments, and the mouse ADAM6 locus ispresent immediately adjacent to the 3′ end of the human V_(H) genesegments, or between two human V_(H) gene segments. In one embodiment,at least 89 mouse V_(H) gene segments are removed and replaced with asingle human V_(H) gene segment, and the mouse ADAM6 locus is presentimmediately adjacent to the 3′ end of the human V_(H) gene segment. In aspecific embodiment, the mouse ADAM6 locus is present 3′ of the V_(H)gene segment within about 20 kilo bases (kb) to about 40 kilo bases (kb)of the 3′ terminus of the inserted human V_(H) gene segment. In aspecific embodiment, the mouse ADAM6 locus is present 3′ of the V_(H)gene segment within about 29 kb to about 31 kb of the 3′ terminus of theinserted human V_(H) gene segment. In a specific embodiment, the mouseADAM6 locus is present within about 30 kb of the 3′ terminus of theinserted human V_(H) gene segment. In a specific embodiment, the mouseADAM6 locus is present within about 30,184 bp of the 3′ terminus of theinserted human V_(H) gene segment.

In a specific embodiment, the replacement includes human gene segmentsV_(H)1-69 and D_(H)-1, and the mouse ADAM6 locus is present downstreamof the V_(H)1-69 gene segment and upstream of the D_(H)1-1 gene segment.In a specific embodiment, the mouse ADAM6 locus is present between ahuman V_(H)1-69 gene segment and a human D_(H)1-1 gene segment, whereinthe 5′ end of the mouse ADAM6 locus is about 258 bp from the 3′ terminusof the human V_(H)1-69 gene segment and the 3′ end of the ADAM6 locus isabout 3,263 bp 5′ of the human D_(H)1-1 gene segment. In a specificembodiment, the mouse ADAM6 locus comprises SEQ ID NO:3 or a fragmentthereof that confers ADAM6 function within cells of the mouse. In aspecific embodiment, the mouse ADAM6 locus comprises SEQ ID NO: 73 or afragment thereof that confers ADAM6 function within cells of the mouse.In a specific embodiment, the mouse ADAM6 locus comprises SEQ ID NO: 77or a fragment thereof that confers ADAM6 function within cells of themouse. In a specific embodiment, the arrangement of human gene segmentsis then the following (from upstream to downstream with respect todirection of transcription of the human gene segments): humanV_(H)1-69-mouse ADAM6 locus-human D_(H)1-1. In one embodiment, theorientation of one or more of mouse ADAM6a and mouse ADAM6b of the mouseADAM6 locus is opposite with respect to direction of transcription ascompared with the orientation of the human gene segments. Alternatively,the mouse ADAM6 locus is present 5′ to, or upstream of, the single humanV_(H) gene segment.

In a specific embodiment, the replacement includes human gene segmentsV_(H)1-2 and D_(H)1-1, and the mouse ADAM6 locus is present upstream ofthe V_(H)1-2 gene segment and upstream of the D_(H)1-1 gene segment. Ina specific embodiment, the mouse ADAM6 locus is present upstream, or 5′,of a human V_(H)1-2 gene segment and a human D_(H)1-1 gene segment,wherein the 5′ end of the mouse ADAM6 locus is about 32,833 bp from the5′ terminus of the human V_(H)1-2 gene segment and the 3′ end of theADAM6 locus is about 18,078 bp from the 5′ terminus of the humanV_(H)1-2 gene segment. In a specific embodiment, the mouse ADAMS locuscomprises SEQ ID NO:3 or a fragment thereof that confers ADAM6 functionwithin cells of the mouse. In a specific embodiment, the mouse ADAM6locus comprises SEQ ID NO: 73 or a fragment thereof that confers ADAM6function within cells of the mouse. In a specific embodiment, the mouseADAM6 locus comprises SEQ ID NO: 77 or a fragment thereof that confersADAM6 function within cells of the mouse. In a specific embodiment, thearrangement of human gene segments is then the following (from upstreamto downstream with respect to direction of transcription of the humangene segments): mouse ADAM6 locus-human V_(H)1-2-human D_(H)1-1. In oneembodiment, the orientation of one or more of mouse ADAM6a and mouseADAM6b of the mouse ADAM6 locus is opposite with respect to direction oftranscription as compared with the orientation of the human genesegments. Alternatively, the mouse ADAM6 locus is present 3′ to, ordownstream of, the single human V_(H) gene segment.

Similarly, a mouse modified with one or more human V_(L) gene segments(e.g., Vκ or Vλ segments) replacing all or substantially all endogenousmouse V_(H) gene segments can be modified so as to either maintain theendogenous mouse ADAM6 locus, as described above, e.g., by employing atargeting vector having a downstream homology arm that includes a mouseADAM6 locus or functional fragment thereof, or to replace a damagedmouse ADAM6 locus with an ectopic sequence positioned between two humanV_(L) gene segments or between the human V_(L) gene segments and a D_(H)gene segment (whether human or mouse, e.g., Vλ+m/hD_(H)), or a J genesegment (whether human or mouse, e.g., Vκ+J_(H)). In one embodiment, thereplacement includes two or more human V_(L) gene segments, and themouse ADAM6 locus or functional fragment thereof is present between thetwo 3′-most V_(L) gene segments. In a specific embodiment, thearrangement of human V_(L) gene segments is then the following (fromupstream to downstream with respect to direction of transcription of thehuman gene segments): human V_(L)3′-1-mouse ADAM6 locus-human V_(L)3′.In one embodiment, the orientation of one or more of mouse ADAM6a andmouse ADAM6b of the mouse ADAM6 locus is opposite with respect todirection of transcription as compared with the orientation of the humanVL gene segments. Alternatively, the mouse ADAM6 locus is present in theintergenic region between the 3′-most human V_(L) gene segment and the5′-most D_(H) gene segment. This can be the case whether the 5′-mostD_(H) segment is mouse or human.

In one aspect, a mouse is provided with a replacement of one or moreendogenous mouse V_(H) gene segments, and that comprises at least oneendogenous mouse D_(H) gene segment. In such a mouse, the modificationof the endogenous mouse V_(H) gene segments can comprise a modificationof one or more of the 3′-most V_(H) gene segments, but not the 5′-mostD_(H) gene segment, where care is taken so that the modification of theone or more 3′-most V_(H) gene segments does not disrupt or render theendogenous mouse ADAM6 locus nonfunctional. For example, in oneembodiment the mouse comprises a replacement of all or substantially allendogenous mouse V_(H) gene segments with a single human V_(H) genesegment, and the mouse comprises one or more endogenous D_(H) genesegments and a functional endogenous mouse ADAM6 locus.

In another embodiment, the mouse comprises the modification ofendogenous mouse 3′-most V_(H) gene segments, and a modification of oneor more endogenous mouse D_(H) gene segments, and the modification iscarried out so as to maintain the integrity of the endogenous mouseADAM6 locus to the extent that the endogenous ADAM6 locus remainsfunctional. In one example, such a modification is done in two steps:(1) replacing the 3′-most endogenous mouse V_(H) gene segments with asingle human V_(H) gene segments employing a targeting vector with anupstream homology arm and a downstream homology arm wherein thedownstream homology arm includes all or a portion of a functional mouseADAM6 locus; (2) then replacing and endogenous mouse D_(H) gene segmentwith a targeting vector having an upstream homology arm that includes aall or a functional portion of a mouse ADAM6 locus.

In various aspects, employing mice that contain an ectopic sequence thatencodes a mouse ADAM6 protein or an ortholog or homolog or functionalhomolog thereof are useful where modifications disrupt the function ofendogenous mouse ADAM6. The probability of disrupting endogenous mouseADAM6 function is high when making modifications to mouse immunoglobulinloci, in particular when modifying mouse immunoglobulin heavy chainvariable regions and surrounding sequences. Therefore, such mice provideparticular benefit when making mice with immunoglobulin heavy chain locithat are deleted in whole or in part, are humanized in whole or in part,or are replaced (e.g., with Vκ or Vλ sequences) in whole or in part.Methods for making the genetic modifications described for the micedescribed below are known to those skilled in the art.

Mice containing an ectopic sequence encoding a mouse ADAM6 protein, or asubstantially identical or similar protein that confers the fertilitybenefits of a mouse ADAM6 protein, are particularly useful inconjunction with modifications to a mouse immunoglobulin heavy chainvariable gene locus that disrupt or delete the endogenous mouse ADAM6sequence. Although primarily described in connection with mice thatexpress antibodies with human variable regions and mouse constantregions, such mice are useful in connection with any geneticmodifications that disrupt endogenous mouse ADAM6 genes. Persons ofskill will recognize that this encompasses a wide variety of geneticallymodified mice that contain modifications of mouse immunoglobulin heavychain variable gene loci. These include, for example, mice with adeletion or a replacement of all or a portion of mouse immunoglobulinheavy chain gene segments, regardless of other modifications.Non-limiting examples are described below.

In some aspects, genetically modified mice are provided that comprise anectopic mouse, rodent, or other ADAM6 gene (or ortholog or homolog orfragment) functional in a mouse, and one or more human immunoglobulinvariable and/or constant region gene segments. In various embodiments,other ADAM6 gene orthologs or homologs or fragments functional in amouse may include sequences from bovine, canine, primate, rabbit orother non-human sequences.

In one aspect, a mouse is provided that comprises an ectopic ADAM6sequence that encodes a functional ADAM6 protein, a replacement of allor substantially all mouse V_(H) gene segments with a single human V_(H)gene segment; a replacement of an or substantially all mouse D_(H) genesegments with one or more human D_(H) gene segments; and a replacementof all or substantially all mouse J_(H) gene segments with one or morehuman J_(H) gene segments.

In one embodiment, the mouse further comprises a replacement of a mouseC_(H)1 nucleotide sequence with a human C_(H)1 nucleotide sequence. Inone embodiment, the mouse further comprises a replacement of a mousehinge nucleotide sequence with a human hinge nucleotide sequence. In oneembodiment, the mouse further comprises a replacement of animmunoglobulin light chain variable locus (V_(L) and J_(L)) with a humanimmunoglobulin light chain variable locus. In one embodiment, the mousefurther comprises a replacement of a mouse immunoglobulin light chainconstant region nucleotide sequence with a human immunoglobulin lightchain constant region nucleotide sequence. In a specific embodiment, theV_(L), J₁, and C_(L) are immunoglobulin κ light chain sequences. In aspecific embodiment, the mouse comprises a mouse C_(H)2 and a mouseC_(H)3 immunoglobulin constant region sequence fused with a human hingeand a human C_(H)1 sequence, such that the mouse immunoglobulin locirearrange to form a gene that encodes a binding protein comprising (a) aheavy chain that has a human variable region, a human C_(H)1 region, ahuman hinge region, and a mouse C_(H)2 and a mouse C_(H)3 region; and(b) a gene that encodes an immunoglobulin light chain that comprises ahuman variable domain and a human constant region.

In one aspect, a mouse is provided that comprises an ectopic ADAM6sequence that encodes a functional ADAM6 protein, a replacement of allor substantially all mouse V_(H) gene segments with one or more humanV_(L) gene segments, and optionally a replacement of all orsubstantially all D_(H) gene segments and/or J_(H) gene segments withone or more human D_(H) gene segments and/or human J_(H) gene segments,or optionally a replacement of all or substantially all D_(H) genesegments and J_(H) gene segments with one or more human J_(L) genesegments.

In one embodiment, the mouse comprises a replacement of all orsubstantially all mouse V_(H), D_(H), and J_(H) gene segments with oneor more V_(L), one or more D_(H), and one or more J gene segments (e.g.,Jκ or Jλ), wherein the gene segments are operably linked to anendogenous mouse hinge region, wherein the mouse forms a rearrangedimmunoglobulin chain gene that contains, from 5′ to 3′ in the directionof transcription, human V_(L)-human or mouse D_(H)-human or mouseJ-mouse hinge-mouse C_(H)2-mouse C_(H)3. In one embodiment, the J regionis a human Jκ region. In one embodiment, the J region is a human J_(H)region. In one embodiment, the J region is a human Jλ region. In oneembodiment, the human V_(L) region is selected from a human Vλ regionand a human Vκ region.

In specific embodiments, the mouse expresses a single variable domainantibody having a mouse or human constant region and a variable regionderived from a human Vκ, a human D_(H) and a human Jκ; a human Vκ, ahuman D_(H), and a human J_(H); a human Vλ, a human D_(H), and a humanJλ; a human Vλ, a human D_(H), and a human J_(H); a human Vκ, a humanD_(H), and a human Jλ; a human Vλ, a human D_(H), and a human Jκ. Inspecific embodiment, recombination recognition sequences are modified soas to allow for productive rearrangements to occur between recited V, D,and J gene segments or between recited V and J gene segments.

In one aspect, a mouse is provided that comprises an ectopic ADAM6sequence that encodes a functional ADAM6 protein (or ortholog or homologor functional fragment thereof), a replacement of all or substantiallyall mouse V_(H) gene segments with one or more human V_(L) genesegments, a replacement of all or substantially all mouse D_(H) genesegment and J_(H) gene segments with human J_(L) gene segments; whereinthe mouse lacks a C_(H)1 and/or hinge region.

In one embodiment, the mouse lacks a sequence encoding a C_(H)1 domain,in one embodiment, the mouse lacks a sequence encoding a hinge region.In one embodiment, the mouse lacks a sequence encoding a C_(H)1 domainand a hinge region.

In a specific embodiment, the mouse expresses a binding protein thatcomprises a human immunoglobulin light chain variable domain (λ or κ)fused to a mouse C_(H)2 domain that is attached to a mouse C_(H)3domain.

In one aspect, a mouse is provided that comprises an ectopic ADAM6sequence that encodes a functional ADAM6 protein (or ortholog or homologor functional fragment thereof), a replacement of all or substantiallyall mouse V_(H) gene segments with one or more human V_(L) genesegments, a replacement of all or substantially all mouse D_(H) andJ_(H) gene segments with human J_(L) gene segments.

In one embodiment, the mouse comprises a deletion of an immunoglobulinheavy chain constant region gene sequence encoding a C_(H)1 region, ahinge region, a C_(H)1 and a hinge region, or a C_(H)1 region and ahinge region and a C_(H)2 region.

In one embodiment, the mouse makes a single variable domain bindingprotein comprising a homodimer selected from the following: (a) humanV_(L)-mouse C_(H)1-mouse C_(H)2-mouse C_(H)3; (b) human V_(L)-mousehinge-mouse C_(H)2-mouse C_(H)3; (c) human V_(L)-mouse C_(H)2-mouseC_(H)3.

In one aspect, a mouse is provided with a disabled endogenous heavychain immunoglobulin locus, comprising a disabled or deleted endogenousmouse ADAM6 locus, wherein the mouse comprises a nucleic acid sequencethat expresses a human or mouse or human/mouse or other chimericantibody. In one embodiment, the nucleic acid sequence is present on atransgene integrated that is randomly integrated into the mouse genome.In one embodiment, the nucleic acid sequence is on an episome (e.g., achromosome) not found in a wild-type mouse.

In one embodiment, the mouse further comprises a disabled endogenousimmunoglobulin light chain locus. In a specific embodiment, theendogenous immunoglobulin light chain locus is selected from a kappa (κ)and a lambda (λ) light chain locus. In a specific embodiment, the mousecomprises a disabled endogenous κ light chain locus and a disabled λlight chain locus, wherein the mouse expresses an antibody thatcomprises a human immunoglobulin heavy chain variable domain and a humanimmunoglobulin light chain domain. In one embodiment, the humanimmunoglobulin light chain domain is selected from a human κ light chaindomain and a human λ light chain domain.

In one aspect, a genetically modified animal is provided that expressesa chimeric antibody and expresses an ADAM6 protein or ortholog orhomolog thereof that is functional in the genetically modified animal.

In one embodiment, the genetically modified animal is selected from amouse and a rat. In one embodiment, the genetically modified animal is amouse, and the ADAM6 protein or ortholog or homolog thereof is from amouse strain that is a different strain than the genetically modifiedanimal. In one embodiment, the genetically modified animal is a rodentof family Cricetidae (e.g., a hamster, a New World rat or mouse, avole), and the ADAM6 protein ortholog or homolog is from a rodent offamily Muridae (e.g., true mouse or rat, gerbil, spiny mouse, crestedrat). In one embodiment, the genetically modified animal is a rodent ofthe family Muridae, and the ADAM6 protein ortholog or homolog is from arodent of family Cricetidae.

In one embodiment, the chimeric antibody comprises a human variabledomain and a constant region sequence of a rodent. In one embodiment,the rodent is selected from a rodent of the family Cricetidae and arodent of family Muridae. In a specific embodiment, the rodent of thefamily Cricetidae and of the family Muridae is a mouse. In a specificembodiment, the rodent of the family Cricetidae and of the familyMuridae is a rat. In one embodiment, the chimeric antibody comprises ahuman variable domain and a constant domain from an animal selected froma mouse or rat; in a specific embodiment, the mouse or rat is selectedfrom the family Cricetidae and the family Muridae. In one embodiment,the chimeric antibody comprises a human heavy chain variable domain, ahuman light chain variable domain and a constant region sequence derivedfrom a rodent selected from mouse and rat, wherein the human heavy chainvariable domain and the human light chain are cognate. In a specificembodiment, cognate includes that the human heavy chain and the humanlight chain variable domains are from a single B cell that expresses thehuman light chain variable domain and the human heavy chain variabledomain together and present the variable domains together on the surfaceof an individual B cell.

In one embodiment, the chimeric antibody is expressed from animmunoglobulin locus. In one embodiment, the heavy chain variable domainof the chimeric antibody is expressed from a rearranged endogenousimmunoglobulin heavy chain locus. In one embodiment, the light chainvariable domain of the chimeric antibody is expressed from a rearrangedendogenous immunoglobulin light chain locus. In one embodiment, theheavy chain variable domain of the chimeric antibody and/or the lightchain variable domain of the chimeric antibody is expressed from arearranged transgene (e.g., a rearranged nucleic acid sequence derivedfrom an unrearranged nucleic acid sequence integrated into the animal'sgenome at a locus other than an endogenous immunoglobulin locus). In oneembodiment, the light chain variable domain of the chimeric antibody isexpressed from a rearranged transgene (e.g., a rearranged nucleic acidsequence derived from an unrearranged nucleic acid sequence integratedinto the animal's genome at a locus other than an endogenousimmunoglobulin locus).

In a specific embodiment, the transgene is expressed from atranscriptionally active locus, e.g., a ROSA26 locus, e.g., a murine(e.g., mouse) ROSA26 locus.

In one aspect, a non-human animal is provided, comprising a humanizedimmunoglobulin heavy chain locus, wherein the humanized immunoglobulinheavy chain locus comprises a non-human ADAM6 sequence or ortholog orhomolog thereof.

In one embodiment, the non-human ADAM6 ortholog or homolog is a sequencethat is orthologous and/or homologous to a mouse ADAM6 sequence, whereinthe ortholog or homolog is functional in the non-human animal.

In one embodiment, the non-human animal is a rodent selected from amouse, a rat, and a hamster.

In one embodiment, the non-human animal is selected from a mouse, a rat,and a hamster and the ADAM6 ortholog or homolog is from a non-humananimal selected from a mouse, a rat, and a hamster. In a specificembodiment, the non-human animal is a mouse and the ADAM6 ortholog orhomolog is from an animal that is selected from a different mousespecies, a rat, and a hamster. In specific embodiment, the non-humananimal is a rat, and the ADAM6 ortholog or homolog is from a rodent thatis selected from a different rat species, a mouse, and a hamster. In aspecific embodiment, the non-human animal is a hamster, and the ADAM6ortholog or homolog is form a rodent that is selected from a differenthamster species, a mouse, and a rat.

In a specific embodiment, the non-human animal is from the suborderMyomorpha, and the ADAM6 sequence is from an animal selected from arodent of superfamily Dipodoidea and a rodent of the superfamilyMuroidea. In a specific embodiment, the rodent is a mouse of superfamilyMuroidea, and the ADAM6 ortholog or homolog is from a mouse or a rat ora hamster of superfamily Muroidea.

In one embodiment, the humanized heavy chain locus comprises a singlehuman V_(H) gene segment, one or more human D_(H) gene segments and oneor more human J_(H) gene segments. In a specific embodiment, the humanV_(H) gene segment, one or more human D_(H) gene segments and one ormore human J_(H) gene segments are operably linked to one or more human,chimeric and/or rodent (e.g., mouse or rat) constant region genes. Inone embodiment, the constant region genes are mouse. In one embodiment,the constant region genes are rat. In one embodiment, the constantregion genes are hamster. In one embodiment, the constant region genescomprise a sequence selected from a hinge, a C_(H)2, a C_(H)3, and acombination thereof. In specific embodiment, the constant region genescomprise a hinge, a C_(H)2, and a C_(H)3 sequence.

In one embodiment, the non-human ADAM6 sequence is contiguous with ahuman immunoglobulin heavy chain sequence. In one embodiment, thenon-human ADAM6 sequence is positioned within a human immunoglobulinheavy chain sequence. In a specific embodiment, the human immunoglobulinheavy chain sequence comprises a V, D and/or J gene segment.

In one embodiment, the non-human ADAM6 sequence is juxtaposed with a Vgene segment. In one embodiment, the non-human ADAM6 sequence ispositioned between two V gene segments. In one embodiment, the non-humanADAM6 sequence is juxtaposed between a V and a D gene segment. In oneembodiment, the mouse ADAM6 sequence is positioned between a V and a Jgene segment. In one embodiment, the mouse ADAM6 sequence is juxtaposedbetween a D and a J gene segment.

In one aspect, a genetically modified non-human animal is provided,comprising a B cell that expresses a human V_(H) domain cognate with ahuman V_(L) domain from an immunoglobulin locus, wherein the non-humananimal expresses a non-immunoglobulin non-human protein from theimmunoglobulin locus. In one embodiment, the non-immunoglobulinnon-human protein is an ADAM protein. In a specific embodiment, the ADAMprotein is an ADAM6 protein or homolog or ortholog or functionalfragment thereof.

In one embodiment the non-human animal is a rodent (e.g., mouse or rat).In one embodiment, the rodent is of family Muridae. In one embodiment,the rodent is of subfamily Murinae. In a specific embodiment, the rodentof subfamily Murinae is selected from a mouse and a rat.

In one embodiment, the non-immunoglobulin non-human protein is a rodentprotein. In one embodiment, the rodent is of family Muridae. In oneembodiment, the rodent is of subfamily Murinae. In a specificembodiment, the rodent is selected from a mouse, a rat, and a hamster.

In one embodiment, the human V_(H) and V_(L) domains are attacheddirectly or through a linker to an immunoglobulin constant domainsequence. In a specific embodiment, the constant domain sequencecomprises a sequence selected from a hinge, a C_(H)2 a C_(H)3, and acombination thereof. In a specific embodiment, the human V_(L) domain isselected from a Vκ or a Vλ domain.

In one aspect, a genetically modified non-human animal is provided,comprising in its germline a human immunoglobulin sequence, wherein thesperm of a male non-human animal is characterized by an in vivomigration defect. In one embodiment, the in vivo migration defectcomprises an inability of the sperm of the male non-human animal tomigrate from a uterus through an oviduct of a female non-human animal ofthe same species. In one embodiment, the non-human animal lacks anucleotide sequence that encodes and ADAM6 protein or functionalfragment thereof. In a specific embodiment, the ADAM6 protein orfunctional fragment thereof includes an ADAM6a and/or an ADAM6b proteinor functional fragments thereof. In one embodiment, the non-human animalis a rodent. In a specific embodiment, the rodent is selected from amouse, a rat, and a hamster.

In one aspect, a non-human animal is provided, comprising a humanimmunoglobulin sequence contiguous with a non-human sequence thatencodes an ADAM6 protein or ortholog or homolog or functional fragmentthereof. In one embodiment, the non-human animal is a rodent. In aspecific embodiment, the rodent is selected from a mouse, a rat, and ahamster.

In one embodiment, the human immunoglobulin sequence is animmunoglobulin heavy chain sequence. In one embodiment, theimmunoglobulin sequence comprises a single V_(H) gene segments. In oneembodiment, the human immunoglobulin sequence comprises one or moreD_(H) gene segments. In one embodiment, the human immunoglobulinsequence comprises one or more J_(H) gene segments. In one embodiment,the human immunoglobulin sequence comprises a single V_(H) genesegments, one or more D_(H) gene segments and one or more J_(H) genesegments.

In one embodiment, the immunoglobulin sequence comprises a single V_(H)gene segment that is associated with polymorphism in natural humanrepertoires. In a specific embodiment, the single V_(H) gene segment isselected from human V_(H)1-2, V_(H)1-69, V_(H)2-26, V_(H)2-70, orV_(H)3-23. In another specific embodiment the single V_(H) gene segmentis V_(H)1-2. In another specific embodiment, the single V_(H) genesegment is V_(H)1-69.

In one embodiment, the immunoglobulin sequence comprises a single V_(H)gene segment that is associated with multiple copy number in naturalhuman repertoires. In a specific embodiment, the single V_(H) genesegment is selected from human V_(H)1-2, V_(H)1-69, V_(H)2-26,V_(H)2-70, or V_(H)3-23. In another specific embodiment the single V_(H)gene segment is V_(H)1-2. In another specific embodiment, the singleV_(H) gene segment is V_(H)1-69.

In various embodiments, the V_(H) gene segment is selected fromV_(H)6-1, V_(H)1-2, V_(H)1-3, V_(H)2-5, V_(H)3-7, V_(H)1-8, V_(H)3-9,V_(H)3-11, V_(H)3-13, V_(H)3-15, V_(H)3-16, V_(H)1-18, V_(H)3-20,V_(H)3-21, V_(n)3-23, V_(H)1-24, V_(H)2-26, V_(H)4-28, V_(H)3-30,V_(H)4-31, V_(H)3-33, V_(H)4-34, V_(H)3-35, V_(H)3-38, V_(H)4-39,V_(H)3-43, V_(H)1-45, V_(H)1-46, V_(H)3-48, V_(H)3-49, V_(H)5-51,V_(H)3-53, V_(H)1-58, V_(H)4-59, V_(H)4-61, V_(H)3-64, V_(H)3-66,V_(H)1-69, V_(H)2-70, V_(H)3-72, V_(H)3-73 and V_(H)3-74.

In various embodiments, the V_(H) gene segment is selected from Table 1and is represented in natural human repertoires by five or more alleles.In a specific embodiment the V_(H) gene is selected from V_(H)1-2,V_(H)1-69, V_(H)2-5, V_(H)2-70, V_(H)3-15, V_(H)3-23, V_(H)3-30,V_(H)3-33, V_(H)3-49, V_(H)3-64, V_(H)4-4, V_(H)4-28, V_(H)4-30-2,V_(H)4- 30-4, V_(n)4-31, V_(H)4-34, V_(H)4-39, V_(H)4-59, V_(H)4-61,V_(H)5-51 and V_(H)7-4-1.

In one embodiment, the non-human animal is a mouse, and the mousecomprises a replacement of endogenous mouse V_(H) gene segments with asingle human V_(H) gene segments, wherein the human V_(H) gene segmentis operably linked to a mouse C_(H) region gene, such that the mouserearranges the human V_(H) gene segment and expresses a reverse chimericimmunoglobulin heavy chain that comprises a human V_(H) domain and amouse C_(H). In one embodiment, 90-100% of unrearranged mouse V_(H) genesegments are replaced with one unrearranged human V_(H) gene segment. Ina specific embodiment, all or substantially all of the endogenous mouseV_(H) gene segments are replaced with one unrearranged human V_(H) genesegment. In one embodiment, the replacement is with an unrearrangedhuman V_(H)1-69 gene segment. In one embodiment, the replacement is withan unrearranged human V_(H)1-2 gene segment. In one embodiment, thereplacement is with an unrearranged human V_(H)2-26 gene segment. In oneembodiment, the replacement is with an unrearranged human V_(H)2-70 genesegment. In one embodiment, the replacement is with an unrearrangedhuman V_(H)3-23 gene segment.

In one embodiment, the mouse comprises a replacement of all mouse D_(H)and J_(H) segments with at least one unrearranged human D_(H) segmentand at least one unrearranged human J_(H) segment. In one embodiment,the at least one unrearranged human D_(H) segment is selected from 1-1,1-7, 1-26, 2-8, 2-15, 3-3, 3-10, 3-16, 3-22, 5-5, 5-12, 6-6, 6-13, 7-27,and a combination thereof. In one embodiment, the at least oneunrearranged human J_(H) segment is selected from 1, 2, 3, 4, 5, 6, anda combination thereof.

In various embodiments, the human immunoglobulin sequence is in operablelinkage with a constant region in the germline of the non-human animal(e.g., the rodent, e.g., the mouse, rat, or hamster). In one embodiment,the constant region is a human, chimeric human/mouse or chimerichuman/rat or chimeric human/hamster, a mouse, a rat, or a hamsterconstant region. In one embodiment, the constant region is a rodent(e.g., mouse or rat or hamster) constant region. In a specificembodiment, the rodent is a mouse or rat. In various embodiments, theconstant region comprises at least a C_(H)2 domain and a C_(H) ³ domain.

In one embodiment, the human immunoglobulin heavy chain sequence islocated at an immunoglobulin heavy chain locus in the germline of thenon-human animal (e.g., the rodent, e.g., the mouse or rat or hamster).In one embodiment, the human immunoglobulin heavy chain sequence islocated at a non-immunoglobulin heavy chain locus in the germline of thenon-human animal, wherein the non-heavy chain locus is atranscriptionally active locus. In a specific embodiment, the non-heavychain locus is a ROSA26 locus.

In various aspects, the non-human animal further comprises a humanimmunoglobulin light chain sequence (e.g., one or more unrearrangedlight chain V and J sequences, or one or more rearranged VJ sequences)in the germline of the non-human animal. In a specific embodiment, theimmunoglobulin light chain sequence is an immunoglobulin κ light chainsequence. In one embodiment, the human immunoglobulin light chainsequence comprises one or more V_(L) gene segments. In one embodiment,the human immunoglobulin light chain sequence comprises one or moreJ_(L) gene segments. In one embodiment, the human immunoglobulin lightchain sequence comprises one or more V_(L) gene segments and one or moreJ_(L) gene segments. In a specific embodiment, the human immunoglobulinlight chain sequence comprises at least 16 Vκ gene segments and five Jκgene segments. In a specific embodiment, the human immunoglobulin lightchain sequence comprises at least 30 Vκ gene segments and five Jκ genesegments. In a specific embodiment, the human immunoglobulin light chainsequence comprises at least 40 Vκ gene segments and five Jκ genesegments. In various embodiments, the human immunoglobulin light chainsequence is in operable linkage with a constant region in the germlineof the non-human animal (e.g., rodent, e.g., mouse or rat or hamster).In one embodiment, the constant region is a human, chimerichuman/rodent, mouse, rat, or hamster constant region. In a specificembodiment, the constant region is a mouse or rat constant region. In aspecific embodiment, the constant region is a mouse κ constant (mCκ)region or a rat κ constant (rCκ) region.

In one embodiment, the non-human animal is a mouse and the mousecomprises a replacement of all or substantially all Vκ and Jκ genesegments with at least six human Vκ gene segments and at least one Jκgene segment. In one embodiment, all or substantially all Vκ and Jκ genesegments are replaced with at least 16 human Vκ gene segments (human Vκ)and at least one Jκ gene segment. In one embodiment, all orsubstantially all Vκ and Jκ gene segments are replaced with at least 30human Vκ gene segments and at least one Jκ gene segment. In oneembodiment, all or substantially all Vκ and Jκ gene segments arereplaced with at least 40 human Vκ gene segments and at least one Jκgene segment. In one embodiment, the at least one Jκ gene segmentcomprises two, three, four, or five human Jκ gene segments.

In one embodiment, the human Vκ gene segments comprise Vκ4-1, Vκ5-2,Vκ7-3, Vκ2-4, Vκ1-5, and Vκ1-6. In one embodiment, the Vκ gene segmentscomprise Vκ3-7, Vκ1-8, Vκ1-9, Vκ2-10, Vκ3-11, Vκ1-12, Vκ1-13, Vκ2-14,Vκ3-15 and Vκ1-16. In one embodiment, the human Vκ gene segmentscomprise Vκ1-17, Vκ2-18, Vκ2-19, Vκ3-20, Vκ6-21, Vκ1-22, Vκ1-23, Vκ2-24,Vκ3-25, Vκ2-26, Vκ1-27, Vκ2-28, Vκ2-29, and Vκ2-30. In one embodiment,the human Vκ gene segments comprise Vκ3-31, Vκ1-32, Vκ1-33, Vκ3-34,Vκ1-35, Vκ2-36, Vκ1-37, Vκ2-38, Vκ1-39, and Vκ2-40.

In a specific embodiment, the V gene segments comprise contiguous humanimmunoglobulin κ gene segments spanning the human immunoglobulin κ lightchain locus from Vκ4-1 through Vκ2-40, and the Jκ gene segments comprisecontiguous gene segments spanning the human immunoglobulin κ light chainlocus from Jκ1 through Jκ5.

In one embodiment, the human immunoglobulin light chain sequence islocated at an immunoglobulin light chain locus in the germline of thenon-human animal. In a specific embodiment, the immunoglobulin lightchain locus in the germline of the non-human animal is an immunoglobulinκ light chain locus. In one embodiment, the human immunoglobulin lightchain sequence is located at a non-immunoglobulin light chain locus inthe germline of the non-human animal that is transcriptionally active.In a specific embodiment, the non-immunoglobulin locus is a ROSA26locus.

In one aspect, a method of making a human antibody is provided, whereinthe human antibody comprises variable domains derived from one or morevariable region nucleic acid sequences encoded in a cell of a non-humananimal as described herein.

In one aspect, a method of making an anti-idiotype antibody is provided,wherein the anti-idiotype antibody comprises variable domains derivedfrom one or more variable region nucleic acid sequences encoded in acell of a non-human animal as described herein, the method comprisingexposing a non-human animal as described herein to an antibodycomprising human variable domains. In one embodiment, the anti-idiotypeantibody is specific for or is capable of binding a human heavy chainvariable domain. In one embodiment, the antibody is specific for or iscapable of binding a human light chain variable domain.

In a specific embodiment, the anti-idiotype antibody is specific for oris capable of binding a human heavy chain variable domain, wherein thehuman heavy chain variable domain comprises a rearranged human V_(H)gene segment selected from V_(H)6-1, V_(H)1-2, V_(H)1-3, V_(H)2-5,V_(H)3-7, V_(H)1-8, V_(H)3-9, V_(H)3-11, V_(H)3-13, V_(H)3-15,V_(H)3-16, V_(H)1-18, V_(H)3-20, V_(H)3-21, V_(n)3-23, V_(H)1-24,V_(H)2-26, V_(H)4-28, V_(H)3-30, V_(H)4-31, V_(H)3-33, V_(H)4-34,V_(H)3-35, V_(H)3-38, V_(H)4-39, V_(H)3-43, V_(H)1-45, V_(H)1-46,V_(H)3-48, V_(H)3-49, V_(H)5-51, V_(H)3-53, V_(H)1-58, V_(H)4-59,V_(H)4-61, V_(H)3-64, V_(H)3-66, V_(H)1-69, V_(H)2-70, V_(H)3-72,V_(H)3-73 and V_(H)3-74.

In a specific embodiment, the anti-idiotype antibody is specific for oris capable of binding a human heavy chain variable domain, wherein thehuman heavy chain variable domain comprises a rearranged human V_(H)gene segment selected from V_(H)1-2, V_(H)1-69, V_(H)2-5, V_(H)2-70,V_(H)3-15, V_(H)3-23, V_(H)3-30, V_(H)3-33, V_(H)3-49, V_(H)3-64,V_(H)4-4, V_(H)4-28, V_(H)4-30-2, V_(H)4-30-4, V_(H)4-31, V_(H)4-34,V_(H)4-39, V_(H)4-59, V_(H)4-61, V_(H)5-51 and V_(H)7-4-1.

In a specific embodiment, the anti-idiotype antibody is specific for oris capable of binding a human light chain variable domain, wherein thehuman light chain variable domain comprises a rearranged human Vκ genesegment selected from Vκ4-1, Vκ5-2, Vκ7-3, Vκ2-4, Vκ1-5, Vκ1-6, Vκ3-7,Vκ1-8, Vκ1-9, Vκ2-10, Vκ3-11, Vκ1-12, Vκ1-13, Vκ2-14, Vκ3-15, Vκ1-16,Vκ1-17, Vκ2-18, Vκ2-19, Vκ3-20, Vκ6-21, Vκ1-22, Vκ1-23, Vκ2-24, Vκ3-25,Vκ2-26, Vκ1-27, Vκ2-28, Vκ2-29, Vκ2-30, Vκ3-31, Vκ1-32, Vκ1-33, Vκ3-34,Vκ1-35, Vκ2-36, Vκ1-37, Vκ2-38, Vκ1-39, and Vκ2-40.

In a specific embodiment, the anti-idiotype antibody is specific for oris capable of binding a human light chain variable domain, wherein thehuman light chain variable domain comprises a rearranged human Vκ1-39gene segment.

In a specific embodiment, the anti-idiotype antibody is specific for oris capable of binding a human light chain variable domain, wherein thehuman light chain variable domain comprises a rearranged human Vλ genesegment selected from Vλ3-1, Vλ4-3, Vλ2-8, Vλ3-9, Vλ3-10, Vλ2-11,Vλ3-12, Vλ2-14, Vλ3-16, Vλ2-18, Vλ3-19, Vλ3-21, Vλ3-22, Vλ2-23, Vλ3-25,Vλ3-27, Vλ3-32, Vλ2-33, Vλ2-34, Vλ1-36, Vλ1-40, Vλ7-43, Vλ1-44, Vλ5-45,Vλ7-46, Vλ1-47, Vλ5-48, Vλ9-49, Vλ1-50, Vλ1-51, Vλ5-52, Vλ10-54, Vλ1-55,Vλ6-57, Vλ4-60, Vλ8-61, and Vλ4-69.

In one embodiment, a method of making an anti-idiotype antibody isprovided, wherein the anti-idiotype antibody comprises variable domainsderived from one or more variable region nucleic acid sequences encodedin a cell of a non-human animal that comprises a restrictedimmunoglobulin heavy chain locus comprising a single human V_(H) genesegment, 27 D_(H) gene segments, and six J_(H) gene segments, andwherein the anti-idiotype antibody is specific for or is capable ofbinding a human heavy chain variable domain comprising a rearrangedhuman V_(H)1-69 gene segment, the method comprising exposing thenon-human animal to an antibody comprising the rearranged humanV_(H)1-69 gene segment and isolating the anti-idiotype antibody from thenon-human animal. In a specific embodiment, the single human V_(H) genesegment is selected from a human V_(H)1-2 and a human V_(H)1-69 genesegment.

In one embodiment, a method of making an anti-idiotype antibody isprovided, wherein the anti-idiotype antibody comprises variable domainsderived from one or more variable region nucleic acid sequences encodedin a cell of a non-human animal that comprises a restrictedimmunoglobulin heavy chain locus comprising a single human V_(H) genesegment, 27 D_(H) gene segments, and six J_(H) gene segments, andwherein the anti-idiotype antibody is specific for or is capable ofbinding a human light chain variable domain comprising a rearrangedhuman Vκ1-39 gene segment, the method comprising exposing the non-humananimal to an antibody comprising the human Vκ1-39 gene segment andisolating the antibody from the non-human animal. In a specificembodiment, the single human V_(H) gene segment is selected from a humanV_(H)1-2 and a human V_(H)1-69 gene segment.

In one aspect, a pharmaceutical composition is provided, comprising apolypeptide that comprises antibody or antibody fragment that is derivedfrom one or more variable region nucleic acid sequences isolated from anon-human animal as described herein. In one embodiment, the polypeptideis an antibody. In one embodiment, the polypeptide is a heavy chain onlyantibody. In one embodiment, the polypeptide is a single chain variablefragment (e.g., an scFv).

In one aspect, use of a non-human animal as described herein to make anantibody is provided. In various embodiments, the antibody comprises oneor more variable domains that are derived from one or more variableregion nucleic acid sequences isolated from the non-human animal. In aspecific embodiment, the variable region nucleic acid sequences compriseimmunoglobulin heavy chain gene segments. In a specific embodiment, thevariable region nucleic acid sequences comprise immunoglobulin lightchain gene segments.

EXAMPLES

The following examples are provided so as to describe to those ofordinary skill in the art how to make and use methods and compositionsof the invention, and are not intended to limit the scope of what theinventors regard as their invention. Unless indicated otherwise,temperature is indicated in Celsius, and pressure is at or nearatmospheric.

Example 1

Construction of a Restricted Humanized IgH Locus

A uniquely engineered human heavy chain locus containing a single humanV_(H) gene segment located upstream of all the human D_(H) and J_(H)gene segments may be constructed by homologous recombination usingBacterial Artificial Chromosome (BAC) DNA. Exemplary human V_(H) genesegments employed for construction of such an immunoglobulin heavy chainlocus include polymorphic V_(H) gene segments and/or V_(H) gene segmentsassociated with a variation in copy number, such as, for exampleV_(H)1-2, V_(H)1-69, V_(H)2-26, V_(H)2-70, and V_(H)3-23. VELOCIGENE®genetic engineering technology can be employed for the creation of asingle V_(H) containing heavy chain locus using several targetingconstructs (see, e.g., U.S. Pat. No. 6,586,251 and Valenzuela, D. M. etal., 2003, High-throughput engineering of the mouse genome coupled withhigh-resolution expression analysis. Nature Biotechnology 21(6):652-659).

Exemplary Strategy for Construction of a Human V_(H)1-69 Restricted IgHLocus (FIG. 1).

In the first step, a modified human BAC containing multiple distal (5′)human V_(H) gene segments, including V_(H)1-69, an upstream selectioncassette (e.g., hygromycin) and a 5′ mouse homology arm was targeted byhomologous recombination with a second selection cassette (e.g.,spectinomycin), which also contained a modified recombination signalsequence (Step 1, FIG. 1). This modified recombination signal sequence(RSS) introduced two point mutations (T to A and G to A) in the 3′ RSSregion of the human V_(H)1-69 gene changing the RSS nonamer to theoptimal consensus sequence. Thus, Step 1 resulted in a human genomicfragment containing the human V_(H)1-69 gene segment with a modified 3′RSS, a unique AsiSI restriction site about 180 bp downstream of the RSSand a spectinomycin cassette.

Step 2 included the use of a neomycin (Neo) cassette flanked by Frtsites to delete the selection cassette (hygromycin) and additionalupstream (5′) human V_(H) gene segments. This modification was targeted,by homologous recombination, 5′ to the human V_(H)1-69 gene segment toleave intact about 8.2 kb of the promoter region of human V_(H)1-69 andthe 5′ mouse homology arm.

Step 3 included another selection cassette (spectinomycin) flanked byuniquely engineered restriction sites (e.g., PI-SceI and AsiSI) targetedby homologous recombination to a human genomic fragment containing thefirst three functional human V_(H) gene segments and all the human D_(H)and J_(H) gene segments (FIG. 1). The human genomic fragment waspreviously targeted by homologous recombination with a neomycin cassetteand contained 5′ and 3′ homology arms containing the mouse genomicsequence 5′ and 3′ of the endogenous heavy chain locus including the 3′intronic enhancer and the IgM gene. This modification deleted the 5′mouse genomic sequence and human V_(H) gene segments, leaving about 3.3kb of the V_(H)-D_(H) intergenic region upstream of the human D_(H)1-1gene segment, all of the human D_(H) and J_(H) segments, and the 3′mouse genomic fragment containing the 3′ intronic enhancer and the IgMgene (FIG. 1).

Step 4 was accomplished by using the unique restriction sites (describedabove) to cut followed by ligation of the two modified BACs from Step 2and Step 3, which yielded the final targeting construct. The finaltargeting construct for the creation of a modified heavy chain locuscontaining a human V_(H)1-69 gene segment, all the human D_(H), and allthe human J_(H) gene segments in ES cells contained, from 5′ to 3′, a 5′homology arm containing about 20 kb of mouse genomic sequence upstreamof the endogenous heavy chain locus, a 5′ Frt site, a neomycin cassette,a 3′ Frt site, about 8.2 kb of the human V_(H)1-69 promoter, the humanV_(H)1-69 gene segment with a modified 3′ RSS, 27 human D_(H) genesegments, six human J_(H) segments, and a 3′ homology arm containingabout 8 kb of mouse genomic sequence downstream of the mouse J_(H) genesegments including the 3′ intronic enhancer and IgM gene (FIG. 1).

Exemplary Strategy for Construction of a Human V_(H)1-2 Restricted IgHLocus (FIG. 2).

In a similar fashion, other polymorphic V_(H) gene segments in thecontext of mouse heavy chain constant regions are employed to constructa series of mice having a restricted number immunoglobulin heavy chain Vsegments (e.g., 1, 2, 3, 4, or 5), wherein the V segments arepolymorphic variants of a V gene family member. Exemplary polymorphicV_(H) gene segments are derived from human V_(H) gene segmentsincluding, e.g., V_(H)1-2, V_(H)2-26, V_(H)2-70 and V_(H)3-23. Suchhuman V_(H) gene segments are obtained, e.g., by de novo synthesis(e.g., Blue Heron Biotechnology, Bothell, Wash.) using sequencesavailable on published databases. Thus, DNA fragments encoding eachV_(H) gene are, in some embodiments, generated independently forincorporation into targeting vectors, as described herein. In this way,multiple modified immunoglobulin heavy chain loci comprising arestricted number of V_(H) gene segments are engineered in the contextof mouse heavy chain constant regions. An exemplary targeting strategyfor creating a restricted humanized heavy chain locus containing a humanV_(H)1-2 gene segment, 27 human D_(H) gene segments, and six human J_(H)gene segments is shown in FIG. 2.

Briefly, a modified human BAC clone containing three human V_(H) genesegments (V_(H)6-1, V_(H)1-2, V_(H)1-3), 27 human D_(H) gene segments,and six human J_(H) gene segments (see U.S. Ser. No. 13/404,075; filed24 Feb. 2012, herein incorporated by reference) is used to create arestricted humanized heavy chain locus containing a human V_(H)1-2 genesegment. This modified BAC clone functionally links the aforementionedhuman heavy chain gene segments with the mouse intronic enhancer and theIgM constant region. The restricted human V_(H)1-2 based heavy chainlocus is achieved by two homologous recombinations using the modifiedhuman BAC clone described above. In the first homologous recombination,205 bp of the human V_(H)6-1 gene segment (from about 10 bp upstream(5′) of the V_(H)6-1 start codon in exon 1 to about 63 bp downstream(3′) of the beginning of exon 2) in the modified human BAC clone isdeleted by bacterial homologous recombination using a spectinomycin(aadA) cassette flanked by unique PI-SceI restriction sites (FIG. 2, BHR1). This allows for subsequent removal of the aadA cassette withoutdisrupting other human gene segments within the restricted heavy chainlocus. In the second homologous recombination, the 5′ end of themodified human BAC clone including the entire human V_(H)1-3 genesegment and about 60 bp downstream (3′) of the gene segment is deletedby homologous recombination using a hygromycin cassette containingflanking 5′ AsiSI and 3′ AscI restriction sites (FIG. 2, BHR 2). Asdescribed above, the spectinomycin cassette is optionally removed afterconfirmation of the final targeting vector including deletion of the twohuman V_(H) gene segments flanking the human V_(H)1-2 gene segment (FIG.2, bottom). An exemplary human V_(H)1-2 targeting vector is set forth inSEQ ID NO: 75.

Employing polymorphic V_(H) gene segments in a restricted immunoglobulinheavy chain locus represents a novel approach for generating antibodies,populations of antibodies, and populations of B cells that expressantibodies having heavy chains with diverse CDRs derived from a singlehuman V_(H) gene segment. Exploiting the somatic hypermutation machineryof the host animal along with combinatorial association with rearrangedhuman immunoglobulin light chain variable domains results in theengineering of unique heavy chains and unique V_(H)/V_(L) pairs thatexpand the immune repertoire of genetically modified animals and enhancetheir usefulness as a next generation platform for making humantherapeutics, especially useful as a platform for making neutralizingantibodies specific for human pathogens.

Based on the final desired locus structure, one of the other human V_(H)gene segments may be substituted in a similar fashion using human BACclones containing the desired human V_(H) gene segment. Thus, using thestrategy outlined above for incorporation of additional and/or otherpolymorphic V_(H) gene segments into the mouse immunoglobulin heavychain locus allows for the generation of novel antibody repertoires foruse in neutralizing human pathogens that might otherwise effectivelyevade the host immune system.

Targeted ES cells described above are used as donor ES cells andintroduced into an 8-cell stage mouse embryo by the VELOCIMOUSE® method(supra). Mice bearing a humanized heavy chain locus containing a singlehuman V_(H) gene segment, all the human D_(H) and J_(H) gene segmentsoperably linked to the mouse immunoglobulin constant region genes areidentified by genotyping using a modification of allele assay(Valenzuela et al., supra) that detected the presence of the neomycincassette, the human V_(H) gene segment and a region within the humanD_(H) and J_(H) gene segments as well as endogenous heavy chainsequences. Table 3 sets forth the primers and probes that are used toconfirm mice harboring a restricted heavy chain locus containing asingle human V_(H)1-69 gene segment, 27 human D_(H) gene segments andsix human J_(H) gene segments.

Mice bearing an engineered heavy chain locus that contains a singlehuman V_(H) gene segment can be bred to a FLPe deletor mouse strain(see, e.g., Rodriguez, C. I. et al. (2000) High-efficiency deleter miceshow that FLPe is an alternative to Cre-loxP. Nature Genetics 25:139-140) in order to remove any Frt'ed neomycin cassette introduced bythe targeting vector that is not removed, e.g., at the ES cell stage orin the embryo. Optionally, the neomycin cassette is retained in themice.

Pups are genotyped and a pup heterozygous for a humanized heavy chainlocus containing a single human V_(H) gene segment, all the human D_(H)and J_(H) segments operably linked to the endogenous mouseimmunoglobulin constant genes is selected for characterizing theimmunoglobulin heavy chain repertoire.

TABLE 3 Name SEQ (Region Detected) Sequence (5′-3′) ID NO: hyg Forward:TGCGGCCGAT CTTAGCC  7 (hygromycin Reverse: TTGACCGATT CCTTGCGG  8cassette) Probe: ACGAGCGGGT TCGGCCCATT C  9 neo Forward:GGTGGAGAGG CTATTCGGC 10 (neomycin Reverse: GAACACGGCG GCATCAG 11cassette) Probe: TGGGCACAAC AGACAATCGG CTG 12 higH9T Forward:TCCTCCAACG ACAGGTCCC 13 human (D_(H)-J_(H) Reverse:GATGAACTGA CGGGCACAGG 14 genomic sequence) Probe:TCCCTGGAAC TCTGCCCCGA CACA 15 77h3 Forward: CTCTGTGGAA AATGGTATGG AGATT16 human V_(H)1-69 Reverse: GGTAAGCATA GAAGGTGGGT ATCTTT 17gene segment) Probe: ATAGAACTGT CATTTGGTCC AGCAATCCCA 18 mIgHA7 Forward:TGGTCACCTC CAGGAGCCTC 19 (mouse D_(H)-J_(H) Reverse:GCTGCAGGGT GTATCAGGTG C 20 genomic sequence) Probe:AGTCTCTGCT TCCCCCTTGT GGCTATGAGC 21 88710T Forward:GATGGGAAGA GACTGGTAAC ATTTGTAC 22 (mouse 3′ V_(H) Reverse:TTCCTCTATT TCACTCTTTG AGGCTC 23 genomic sequence) Probe:CCTCCACTGT GTTAATGGCT GCCACAA 24 mIgHd10 Forward:GGTGTGCGAT GTACCCTCTG AAC 25 (mouse 5′ V_(H) Reverse:TGTGGCAGTT TAATCCAGCT TTATC 26 genomic sequence) Probe:CTAAAAATGC TACACCTGGG GCAAAACACC TG 27 mIgHp2 Forward:GCCATGCAAG GCCAAGC 28 (mouse J_(H) Reverse: AGTTCTTGAG CCTTAGGGTG CTAG29 genomic sequence) Probe: CCAGGAAAAT GCTGCCAGAG CCTG 30

Example 2

Reengineering of ADAM Genes into a Restricted Humanized IgH Locus

Mice with humanized immunoglobulin heavy chain loci in which theendogenous variable region gene segments (VDJ) have been replaced and/ordeleted lack expression of endogenous ADAM6 genes. In particular, malemice comprising such humanized immunoglobulin heavy chain locidemonstrate a reduction in fertility. Thus, the ability to express ADAM6was reengineered into mice with humanized, yet restricted, heavy chainloci to perpetuate the modified mouse strains using normal breedingmethods.

Reengineering of ADAM6 Genes into a Human V_(H)1-69 Restricted IgH Locus(FIG. 3).

A restricted immunoglobulin heavy chain locus containing a single humanV_(H)1-69 gene segment located upstream of all the human D_(H) and J_(H)gene segments was reengineered to contain a genomic fragment encodingmouse ADAM6a and ADAM6b (SEQ ID NO: 77) by homologous recombinationusing BAC DNA. This was accomplished by VELOCIGENE® genetic engineeringtechnology (supra) in a series of six steps that included modificationof BAC DNA containing mouse and human sequences that yielded a finaltargeting vector containing a restricted humanized heavy chain locuscontiguous with mouse heavy chain constant regions and mouse ADAM6genes.

First, a mouse genomic fragment that encoded mouse ADAM6a and ADAM6b wasprepared for insertion into a humanized heavy chain locus containing asingle V_(H) gene segments by a series of three bacterial homologousrecombinations involving different selection cassettes to uniquelyposition restriction sites around the mouse ADAM6 genes (FIG. 3, Steps1-3). In the first step, mouse BAC DNA containing a portion of the mouseimmunoglobulin heavy chain locus was targeted with a neomycin cassetteflanked by recombination sites, which was engineered to contain uniqueAsiSI restriction sites. In the second step, the modified mouse fragmentcontaining mouse ADAM6 genes and the neomycin cassette was then targetedto delete the mouse D_(H) and J_(H) gene segments and replace them witha spectinomycin cassette that contained a unique AscI restriction sitepositioned 5′ of the selection gene. In the third step, the doublemodified mouse fragment containing a neomycin cassette positionedbetween the mouse ADAM6 genes and a spectinomycin cassette was targetedto swap out the neomycin cassette for a hygromycin cassette. This wascarried out so that the modified mouse genomic fragment containing theADAM6 genes could be inserted by ligation of compatible genomicfragments into a humanized heavy chain locus containing the single V_(H)gene segment.

In step four, a humanized heavy chain locus containing a human V_(H)1-69gene segment, 27 human D_(H) gene segments, and six human J_(H) genesegments was separately targeted by bacterial homologous recombinationwith a spectinomycin cassette containing unique I-CeuI and AscIrestriction sites at 5′ and 3′ locations in the cassette, respectively(FIG. 3, top left). Following this step, the modified genomic fragmentcontaining a restricted humanized heavy chain locus, neomycin andspectinomycin cassettes and the modified mouse fragment containing theADAM6 genes, hygromycin and spectinomycin cassettes were separatelydigested with I-CeuI and AscI restriction enzymes to create modifiedgenomic fragments for ligation (FIG. 3, middle). In step five, theappropriate digested genomic fragments were purified and ligatedtogether to yield a reengineered humanized heavy chain locus containinga single human V_(H) gene segment, 27 human D_(H) gene segments, sixhuman J_(H) gene segments and an integrated mouse genomic fragmentencoding ADAM6a and ADAM6b with neomycin and hygromycin resistance. Inthe final step (Step 6), the hygromycin cassette was deleted by AsiSIdigestion followed by relegation of the compatible ends.

This step produced the final targeting vector for reinsertion of mouseADAM6a and ADAM6b sequences into a restricted humanized heavy chainlocus, which contained, from 5′ to 3′, a 5′ homology arm containingabout 20 kb of mouse genomic sequence upstream of the endogenous heavychain locus, a 5′ Frt site, a neomycin cassette, a 3′ Frt site, about8.2 kb of the human V_(H)1-69 promoter, the human V_(H)1-69 gene segmentwith a modified 3′ RSS, a mouse genomic fragment containing about 17711bp of mouse genomic sequence including mouse ADAM6a and ADAM6b genes(SEQ ID NO: 77), a human genomic fragment containing 27 human D_(H) andsix human J_(H) gene segments, and a 3′ homology arm containing about 8kb of mouse genomic sequence downstream of the endogenous heavy chainlocus including the intronic enhancer and the IgM constant region gene(Human V_(H)1-69/A6 Targeting Vector, SEQ ID NO: 74; FIG. 3, bottom).

Reengineering of ADAM6 Genes into a Human V_(H)1-2 Restricted IgH Locus(FIG. 4).

A restricted immunoglobulin heavy chain locus containing a single humanV_(H)1-2 gene segment located upstream of all the human D_(H) and J_(H)gene segments is reengineered to contain a genomic fragment encodingmouse ADAM6a and ADAM6b (SEQ ID NO: 73) by homologous recombinationusing BAC DNA. This was accomplished by VELOCIGENE® genetic engineeringtechnology (supra) in a series of steps that included modification ofBAC DNA containing mouse and human sequences that yielded a finaltargeting vector containing a restricted humanized heavy chain locuscontiguous with mouse heavy chain constant regions and mouse ADAM6genes.

A modified human BAC clone containing a single human V_(H)1-2 genesegment flanked by 5′ hygromycin and 3′ spectinomycin cassettes, 27human D_(H) gene segments, six human J_(H) gene segments, a mouse heavychain intronic enhancer, and a mouse IgM constant region (describedabove in Example 1) was modified to contain a genomic fragment encodingmouse ADAM6 genes. This is accomplished by a modified isothermic DNAassembly method referred to herein as oligo-mediated isothermalassembly, which is based on the method described in Gibson et al. (2009,Enzymatic assembly of DNA molecules up to several hundred kilobases,Nature Methods 6(5):343-345; herein incorporated by reference). Thismodified method does not require sequence identity between the ligatedfragments. Instead, sequence identity is imparted by an oligo thatserves to join the two fragments. Further, the oligo serves as atemplate that adds sequence identity to the end of one of the fragments.The extended fragment enables hybridization with the second fragment.Specifically, oligo-mediated isothermal assembly was employed to replacethe hygromycin cassette with a NotI-AscI fragment containing a 20 kbdistal mouse IgH homology arm, the mouse ADAM6a gene, a neomycincassette flanked by Frt sites, and the mouse ADAM6b gene.

Briefly, the modified human BAC clone containing a restricted humanV_(H)1-2 heavy chain locus (FIG. 4, top left) is digested with AsiSI andAscI to remove the hygromycin cassette, and a modified mouse BACcontaining the mouse ADAM6 genes (FIG. 4, top right) is digested withNotI and AscI to remove the fragment containing the 5′ mouse arm andrelease the mouse ADAM6 genes flanking the neomycin cassette. The twodigested BAC fragments are subsequently mixed together with 5′ and 3′joiner oligonucleotides and incubated for 1 hour at 50° C. in anassembly reaction mixture (T5 exonuclease, Phusion DNA polymerase, TaqDNA ligase, 10 mM DTT, 5% PEG8000 (w/v), 1 mM NAD, 0.2 mM dNTPs, 10 mMMgCl₂, and 100 mM Tris-HCl). The 5′ joiner oligo contains a 38 bpoverlap with sequence 5′ of the AsiSI site of the modified human BACclone containing human V_(H)1-2, and a 30 bp overlap with the NotI siteand adjacent 3′ sequence of the modified mouse BAC clone containingADAM6 genes. The 3′ joiner oligo contains a 26 bp overlap with sequence5′ of the AscI site of modified mouse BAC clone containing ADAM6 genes,an AscI site, and a 35 bp overlap with sequence 3′ of the AscI site ofthe modified human BAC clone containing human V_(H)1-2. The assemblyreaction is transformed into E. coli and the correct product is selectedwith kanamycin and spectinomycin selection. To create the finaltargeting vector, the spectinomycin cassette is removed by PI-SceIdigestion followed by religation.

The final targeting vector contains, from 5′ to 3′, a 20 kb distal mouseIgH homology arm, a mouse ADAM6a gene, a 5′ Frt site, a neomycincassette, a 3′ Frt site, a mouse ADAM6b gene, a ˜18 kb human genomicfragment, a human V_(H)1-2 gene segment, a ˜46.6 kb human genomicfragment, an inactivated human V_(H)6-1 gene segment, 27 human D_(H)gene segments, six human J_(H) gene segments, and an 8 kb 3′ mousehomology arm containing a mouse IgH intronic enhancer and IgM constantregion (SEQ ID NO: 76)

Each of the final targeting vectors (described above) were used toelectroporate mouse ES cells that contained a deleted endogenous heavychain locus to created modified ES cells comprising a mouse genomicsequence ectopically placed that comprises mouse ADAM6a and ADAM6bsequences within a restricted humanized heavy chain locus. Positive EScells containing the ectopic mouse genomic fragment within the humanizedheavy chain locus were identified by a quantitative PCR assay usingTAQMAN™ probes (Lie and Petropoulos, 1998, Advances in quantitative PCRtechnology: 5′nuclease assays, Curr Opin Biotechnol 9(1):43-48).

Targeted ES cells described above were used as donor ES cells andintroduced into an 8-cell stage mouse embryo by the VELOCIMOUSE® mouseengineering method (see, e.g., U.S. Pat. Nos. 7,6598,442, 7,576,259,7,294,754). Mice bearing a humanized heavy chain locus containing arestricted number of human gene segments and an ectopic mouse genomicsequence comprising mouse ADAM6a and ADAM6b sequences were identified bygenotyping using a modification of allele assay (Valenzuela et al.,2003) that detected the presence of the mouse ADAM6a and ADAM6b geneswithin the restricted humanized heavy chain locus as well as human heavychain sequences.

Pups are genotyped and a pup heterozygous for a restricted humanizedheavy chain locus containing an ectopic mouse genomic fragment thatcomprises mouse ADAM6a and ADAM6b sequences is selected forcharacterizing mouse ADAM6 gene expression and fertility.

We claim:
 1. A mouse having in its germline: (a) an insertion comprisingan unrearranged human genomic sequence comprising a single human V_(H)gene segment, one or more D_(H) gene segments, and one or more J_(H)gene segments, wherein the single human V_(H) gene segment, one or moreD_(H) gene segments, and one or more J_(H) gene segments are operablylinked to a mouse immunoglobulin heavy chain constant region gene at theendogenous immunoglobulin heavy chain locus, and wherein the singlehuman V_(H) gene segment is V_(H)1-2 or a polymorphic variant thereof,wherein the insertion disrupts the function of an endogenous ADAM6protein, and wherein the disruption of the endogenous ADAM6 function isassociated with a reduction in fertility in male mice; and b) aninsertion comprising a nucleic acid sequence that encodes a mouse ADAM6protein that is functional in a male mouse, wherein the mouse ADAM6protein is expressed if the mouse is a male mouse such that the malemouse has wild-type fertility, wherein the nucleic acid sequence thatencodes the mouse ADAM6 protein is located upstream of the single humanV_(H) gene segment; wherein B cells of the mouse express antibodies inresponse to exposure to an antigen, wherein each antibody includes twoimmunoglobulin light chains paired with two immunoglobulin heavy chains,wherein each heavy chain comprises a human heavy chain variable domainexpressed from a human heavy chain variable region sequence including aV_(H) gene segment that is identical to, or a somatically hypermutatedversion of, the single human V_(H) gene segment.
 2. The mouse of claim1, wherein the single human V_(H) gene segment is a polymorphic variantof V_(H)1-2.
 3. The mouse of claim 1, wherein the mouse comprises adeletion of all functional endogenous V_(H) gene segments.
 4. The mouseof claim 1, wherein the unrearranged human genomic sequence comprises ahuman V_(H)1-2 gene segment, 27 human D_(H) gene segments, and six humanJ_(H) gene segments.
 5. The mouse of claim 1, further comprising one ormore human Vκ gene segments and one or more human Jκ gene segments. 6.The mouse of claim 5, wherein the one or more human Vκ gene segments andone or more human Jκ gene segments are present at an endogenousimmunoglobulin light chain locus.
 7. The mouse of claim 1, wherein themouse is a male mouse.
 8. A cell or tissue derived from the mouse ofclaim 1 or
 7. 9. A method of generating a rearranged humanimmunoglobulin heavy chain variable region sequence that encodes a humanimmunoglobulin heavy chain variable domain, the method comprising: (a)immunizing the mouse of claim 1 with an antigen of interest; (b)allowing said mouse to mount an immune response with respect to theantigen of interest; and (c) identifying or isolating a rearranged humanimmunoglobulin heavy chain variable region sequence that encodes a heavychain variable domain of an antibody from the mouse that binds theantigen of interest.
 10. The method of claim 9, wherein the heavy chainvariable domain includes an amino acid sequence encoded by the singlehuman V_(H) gene segment, wherein the amino acid sequence encoded by thesingle human V_(H) gene segment is at least 75% identical to SEQ ID NO:64.
 11. The method of claim 9, wherein the heavy chain variable domainincludes an amino acid sequence encoded by the single V_(H) genesegment, wherein the amino acid sequence encoded by the single humanV_(H) gene segment encodes an amino acid sequence identical to SEQ IDNO:
 64. 12. A method for modifying an immunoglobulin heavy chain locusof a mouse, comprising: (a) making a first modification of the mouseimmunoglobulin heavy chain locus, wherein the first modificationcomprises an insertion of one or more unrearranged human immunoglobulingene sequences at the mouse immunoglobulin heavy chain locus, includinga single human V_(H) gene segment, one or more D_(H) gene segments, andone or more J_(H) gene segments, wherein the single human V_(H) genesegment, one or more D_(H) gene segments, and one or more J_(H) genesegments are operably linked with a mouse immunoglobulin heavy chainconstant region gene at the endogenous immunoglobulin heavy chain locus,wherein the single human V_(H) gene segment is V_(H)1-2 or a polymorphicvariant thereof, wherein the insertion disrupts the function of anendogenous ADAM6 protein, and wherein the disruption of the endogenousADAM6 function is associated with a reduction in fertility in male mice;and (b) making a second modification of the mouse which comprises aninsertion of a mouse ADAM6 sequence upstream of the single human V_(H)gene segment, wherein the mouse ADAM6 sequence encodes a mouse ADAM6protein that is functional in a male mouse, wherein the functional mouseADAM6 protein is expressed if the mouse is a male mouse such that themale mouse has wild-type fertility.
 13. The method of claim 12, whereinthe first modification comprises the replacement of one or moresequences in the mouse immunoglobulin heavy chain locus with the one ormore unrearranged human immunoglobulin gene sequences.
 14. The method ofclaim 12, wherein the first modification comprises the replacement ofone or more endogenous V_(H) gene segments with the single human V_(H)gene segment in the endogenous immunoglobulin heavy chain locus.
 15. Themethod of claim 12, wherein the first modification comprises thereplacement of an endogenous heavy chain variable gene sequence with theone or more unrearranged human immunoglobulin gene sequences, includingthe single V_(H) gene segment, operably linked with the mouseimmunoglobulin heavy chain constant region gene in the endogenousimmunoglobulin heavy chain locus.
 16. The method of claim 12, whereinthe first and the second modification are made simultaneously.
 17. Amethod for generating an antibody specific against an antigen comprisingthe steps of: (a) immunizing the mouse of claim 1 with the antigen; (b)isolating at least one cell from the mouse producing an antibodyspecific against the antigen; and (c) culturing the at least one cellproducing an antibody of step (b); and (d) obtaining said antibody. 18.The method of claim 17, wherein the culturing in step (c) is performedon at least one hybridoma cell generated from the at least one cellobtained in step (b).
 19. The method of claim 17, wherein the at leastone cell obtained in step (b) is derived from the spleen, a lymph nodeor bone marrow of the mouse from step (a).
 20. The method of claim 17,wherein immunizing with the antigen of step (a) is carried out withprotein, DNA, a combination of DNA and protein, or cells expressing theantigen.
 21. The method of claim 9, wherein the heavy chain variabledomain includes an amino acid sequence encoded by the single human V_(H)gene segment, wherein the amino acid sequence encoded by the singlehuman V_(H) gene segment is at least 90% identical to SEQ ID NO:
 64. 22.The method of claim 9, wherein the heavy chain variable domain includesan amino acid sequence encoded by the single human V_(H) gene segment,wherein the amino acid sequence encoded by the single human V_(H) genesegment is at least 95% identical to SEQ ID NO:
 64. 23. The method ofclaim 9, wherein the heavy chain variable domain includes an amino acidsequence encoded by the single human V_(H) gene segment, wherein theamino acid sequence encoded by the single human V_(H) gene segment is atleast 98% identical to SEQ ID NO:
 64. 24. A method for making a humanantigen-binding protein, comprising the steps of: (a) exposing a mouseof claim 1 to an antigen of interest; (b) allowing the mouse to mount animmune response to the antigen; and (c) obtaining from the mouse a heavychain variable region nucleic acid sequence encoding a human heavy chainvariable domain of an antibody that specifically binds the antigen ofinterest.
 25. The method of claim 24, further comprising the step of (d)linking the human heavy chain variable region nucleic acid sequence to ahuman heavy chain constant region nucleic acid sequence.
 26. The methodof claim 25, further comprising the step of (e) expressing in amammalian cell an antibody comprising the human heavy chain variableregion nucleic acid sequence and the human heavy chain constant regionnucleic acid sequence.